MCAT Official Prep Hub - MCAT Official Prep Independent Question Bank

Answer Key: A Conservation of energy requires that the 15.0 eV photon energy first provides the ionization energy to unbind the electron, and then allows any excess energy to become the electron's kinetic energy. The kinetic energy in this case is 15.0 eV - 13.6 eV = 1.4 eV. Thus the correct answer is A.

A 15.0-eV photon collides with and ionizes a hydrogen atom. If the atom was originally in the ground state (ionization potential =13.6 eV), what is the kinetic energy of the ejected electron? _ A 1.4 eV B 13.6 eV C 15.0 eV D 28.6 eV Energy Conservation: The total energy of the system (photon + atom) before the collision must be equal to the total energy after the collision (ejected electron + remaining ionized atom). Applying the principle: Before: The total energy is the energy of the photon (15.0 eV). After: The total energy is the sum of the kinetic energy (KE) of the ejected electron and the remaining ionized atom (which is essentially a proton since it lost its electron). However, by convention, we assume the ionized atom (proton) has no kinetic energy after the collision. Therefore, we can equate the energy before and after the collision: 15.0 eV (photon energy) = KE (of ejected electron) + 13.6 eV (ionization potential) Solving for KE: Subtract the ionization potential from both sides: KE = 15.0 eV - 13.6 eV KE = 1.4 eV

Answer Key: B The terminal voltage is the voltage provided to the external components of the circuit. The battery voltage ℰ will be reduced by the voltage required to overcome the internal resistance, so V = ℰ - ir. Thus, B is the best answer.

A battery in a circuit has an electromotive force given by ℰ and an internal resistance of r. The battery provides a current i to the circuit. What is the terminal voltage of the battery? _ A ℰ B ℰ - ir C ℰ + ir D ℰ + i2r

Answer Key: B The ideal gas law makes the assumption that molecules have no volume. This assumption is adequate when the gas is at 1 atm, but when the pressure is increased to 500 atm the volume of the gas molecules is no longer negligible.

A gas that occupies 10 L at 1 atm and 25oC will occupy what volume at 500 atm and 25oC? _ A Exactly 0.020 L B Somewhat more than 0.02 L because of the space occupied by the individual gas molecules C Somewhat more than 0.02 L because of the repulsions between the individual gas molecules D Somewhat more than 0.02 L because of the increased number of collisions with the sides of the container

Answer Key: C. Light can be carried along a distance within a transparent material by means of total internal reflection. Thus, C is the best answer.

A glass fiber carries a light digital signal long distances with a minimum loss of amplitude. What optical property of glass allows this phenomenon? _ A Dispersion B Refraction C Reflection D Diffraction

Answer Key: D The work W in lifting a mass m to height h in a gravitational field g is W = mgh. This is an example of the basic definition of work as the product of a force (mg in this case) times a distance (h in this case). If the height is doubled, then the work is doubled for the same mass being lifted. The ratio requested is answer D.

A mass is lifted from the ground to an altitude h1, requiring work W1. The work to lift an identical mass to an altitude h2 is W2. If h2 is twice h1, what is the ratio of W2 to W1? (Note: Assume that the force of gravity does not change between h1 and h2.) _ A 1:2 B √2:1 C √2:2 D 2:1

Answer Key: D This is a Psychology question that falls under content category "Social thinking." The answer to this question is D because the therapist is attempting to encourage the patient to attribute his/her problems to internal controllable factors rather than an uncontrollable internal factor. It is a Scientific Reasoning and Problem Solving question because it requires using the information in the stem to deduce the therapist's strategy.

A patient diagnosed with depression blames all professional failure on personal incompetence. The therapist tries to change the patient's thinking by suggesting that the perceived failures may be due to a lack of effort. The therapist is most likely attempting to change the patient's: _ A self-serving bias. B belief perseverance. C hindsight bias. D locus of control.

Answer Key: D This is a Psychology question that falls under content category "Individual influences on behavior." The answer to this question is D because the diathesis-stress model integrates the influence of biological predispositions and the environment. It is a Knowledge of Scientific Concepts and Principles question because it requires identifying that the therapist is using the diathesis-stress model.

A patient experiences a debilitating depressive episode after the loss of a job. A psychologist suggests that the patient had a genetic predisposition to depression and that unemployment acted as a trigger. The psychologist is using which approach to explain the patient's depression? _ A Rogers's humanistic theory B Beck's cognitive theory C The opponent process model D The diathesis-stress model

Answer Key: A This is a Psychology question that falls under content category "Making sense of the environment." The answer to this question is A because the patient does not remember the therapist explicitly, but the change in his behavior indicates that he has an implicit memory of therapist, which likely results in him becoming less guarded. It is a Scientific Reasoning and Problem Solving question because it requires using the information in the stem to identify the type of memory problems the patient is experiencing.

A patient with Korsakoff syndrome is very guarded toward the therapist and is reluctant to answer the therapist's questions. At subsequent appointments, the patient indicates not recognizing the therapist but is less guarded and more willing to answer questions. This suggests that the patient: _ A has no explicit memory of meeting the therapist but does have an implicit memory of the meeting. B has no episodic memory of meeting the therapist but does have a semantic memory of the meeting. C has no short-term memory of meeting the therapist but does have a long-term memory of the meeting. D has no sensory memory of meeting the therapist but does have a procedural memory of the meeting.

Answer Key: D This is a Psychology question that falls under content category "Attitude and behavior change." The answer to this question is D because the characteristics of the audience are not addressed in the stem. The video combines the central route to persuasion (disease) with the peripheral route (the prestige of the physician). The mention of the physician's affiliation with a prestigious institution is a manipulation of source characteristics. It is a Knowledge of Scientific Concepts and Principles question because it requires knowing the definitions of the terms listed in the response options.

A public health video designed to promote flu shots shows a physician from a prestigious institution delivering facts about how viruses spread. The video also features data on how viruses can expose the body to serious illnesses. The video uses all of the following variables to manipulate attitudes EXCEPT: _ A the peripheral route to persuasion. B the central route to persuasion. C source characteristics. D audience characteristics.

Answer Key: B This is a Psychology question that falls under content category "Attitude and behavior change." The answer to this question is B because when a response results in escape from an aversive stimulus, it is an example of negative reinforcement. It is a Knowledge of Scientific Concepts and Principles question because it requires knowing the definition of negative reinforcement.

A rat in a shuttle box is presented with a tone followed by an electric shock. It can jump over the barrier to the other side of the shuttle box where no shock is delivered. This procedure is repeated over a number of trials. The rat will be conditioned through which type of reinforcement? _ A Positive reinforcement B Negative reinforcement C Positive punishment D Negative punishment

Answer Key: B This is a Psychology question that falls under content category "Attitude and behavior change." The answer to this question is B because a variable ratio schedule leads to high response rates with no predictable pauses. It is a Knowledge of Scientific Concepts and Principles question because it requires knowing the effects of variable ratio schedules on responding.

A rat receives food for pressing a lever on a variable ratio schedule. Which pattern of responding is most likely to be observed? _ A Relatively high response rate with predictable pauses after reinforcement B Relatively high response rate with no predictable pauses C Relatively low response rate with a predictable increase in responding right before reinforcement D Fluctuating response rate with a predictable increase in responding right after reinforcement

Answer Key: B The position of equilibrium in a reaction is determined solely by the difference in free energy between products and reactants. A catalyst speeds the reaction by lowering the activation energy of the reaction. It can do nothing to affect the energies of products and reactants and thus cannot affect the position of the equilibrium. It only allows the reaction to reach equilibrium more quickly. Answer choice B is correct.

A reaction is designed to produce ammonia from the gas phase equilibrium of nitrogen and hydrogen. N2(g) + 3 H2(g) 2 NH3(g) Introducing a catalyst into the system will cause the amount of ammonia at equilibrium: _ A to increase. B to remain the same. C to decrease. D to change in a manner which depends on the value of the equilibrium constant.

Answer Key: B This is a Psychology question that falls under content category "Making sense of the environment." The answer to this question is B because changes in brain size as a function of environmental influences is an example of neural plasticity. It is a Scientific Reasoning and Problem Solving question because it requires using the information about the design of a study to derive the concept under study.

A researcher compares the brain sizes of two groups of rats. Group 1 has been raised in impoverished cages with minimal access to socialization and exercise. Group 2 has been raised in enriched cages with regular access to socialization and exercise. This is best described as a study of: _ A long-term potentiation. B neural plasticity. C hemispheric lateralization. D synaptic reuptake.

Answer Key: C This is a Psychology question that falls under content category "Attitude and behavior change." The answer to this question is C because the variable that is manipulated is the number of responses required for the same amount of food reinforcement. This is best described as two different fixed ratio schedules being compared. It is a Reasoning about the Design and Execution of Research question because it requires deriving the independent variable based on the study design.

A researcher compares the frequency of rats' responses when the rats are presented with one food pellet after every 10 responses to when they are presented with one food pellet every 20 responses. The independent variable in this study is: _ A response frequency. B quantity of primary reinforcement. C different fixed ratio schedules. D different fixed interval schedules.

Answer Key: C The question shows a short polynucleotide containing A, U, C, and G. Given that it is a polynucleotide containing uracil (U), one can conclude that it is RNA. Therefore, the key is C.

A researcher has a short polynucleotide strand with the following base sequence: AUCCCUGG. This strand must be: _ A template DNA. B DNA. C RNA. D a peptide.

Answer Key: D This is a Psychology question that falls under content category "Social thinking." The answer is D because actor-observer bias refers to the actor's tendency to explain his/her own behavior by situational factors whereas the observer tends to explain the actor's behavior by internal stable traits. Thus, an appropriate measure would be to assess whether the actor and the observer attribute the actor's behavior to a relatively stable trait such as intellect. It is a Scientific Reasoning and Problem Solving question because it requires applying the definition of actor-observer bias to predicting the researcher's variables.

A researcher interested in actor-observer bias asks a group of viewer participants to watch a target participant work on a series of puzzles. Which two variables is the researcher most likely to compare in this study? _ A The viewers' memory for the puzzles and the target's memory for the puzzles B The viewers' estimate of the difficulty of the puzzles and the target's estimate of the difficulty of the puzzles C The viewers' likelihood of accurately remembering the target's performance and the target's likelihood of accurately remembering his or her own performance D The viewers' likelihood of attributing the target's performance to intellect and the target's likelihood of attributing his or her own success to intellect

Answer Key: B This is a Psychology question that falls under content category "Individual influences on behavior." The answer to this question is B because the researcher is interested in the structure of the brain, which can be studied through a CAT scan. It is a Knowledge of Scientific Concepts and Principles question because it requires knowing the basic properties of different methods of studying the brain.

A researcher is interested in assessing the size of a patient's brain ventricles. Which method(s) is(are) appropriate for this purpose? I. An EEGII. A CAT scanIII. A PET scan _ A I only B II only C I and III only D II and III only

Answer Key: C This is a Psychology question that falls under content category "Attitude and behavior change." The answer to this question is C because the example does not involve habituation, which refers to loss of response to a repeating stimulus. The procedure of reinforcing successive approximations to the lever press response exemplifies shaping through operant conditioning. Food is used to positively reinforce the responses. It is a Knowledge of Scientific Concepts and Principles question because it requires knowing the definitions of the concepts involved in shaping.

A researcher presents a rat with a food pellet for looking at a lever. When the rat looks at the lever consistently, the researcher stops presenting food for the response and begins to present food if the rat approaches the lever. Eventually the rat is presented with food only after pressing the lever. This method of training exemplifies all of the following EXCEPT: _ A shaping. B positive reinforcement. C habituation. D operant conditioning.

Answer Key: D This is a Psychology question that falls under content category "Attitude and behavior change." The answer to this question is D because the researcher changes the hue after the infant stops responding to the original stimulus. This is an example of habituation. It is a Knowledge of Scientific Concepts and Principles question because it requires knowing the definition of habituation.

A researcher repeatedly presents 1-month-old infants with a color patch. When an infant stops looking at the color patch, the researcher changes the hue of the color patch presented on the next trial. The researcher is using which paradigm to study color perception in infants? _ A Classical conditioning B Operant conditioning C Latent learning D Habituation

Answer Key: C Density is mass/volume. The densities of the four objects are: A. (1.5/0.50) = 3.0 g/ccB. (3.0/0.75) = 4.0 g/ccC. (4.5/1.00) = 4.5 g/ccD. (6.0/1.50) = 4.0 g/cc Thus, answer C with 4.5 g/cc is correct because it has the highest density.

A student measures the mass and volume of four objects. Which object has the highest density? _ A A B B C C D D

Answer Key: C This is a Psychology question that falls under content category "Individual influences on behavior." The answer to this question is C because explaining behavior through self-concept and incongruence is consistent with the humanistic perspective. It is a Scientific Reasoning and Problem Solving question because it requires applying the principles of theory to the example in the question.

A student neglects her studies and spends most of her time engaging in extracurricular activities. When her parents confront her, the student says that all her peers behave the same way. Which explanation for the student's actions is most likely from a proponent of the humanistic perspective? _ A The student is positively reinforced for extracurricular activities and presents her behavior as average to avoid punishment from her parents. B The student uses projection as a defense to reduce the subconscious conflict that arises from neglecting school work. C The student is attempting to reduce the incongruence between the ideal self and the actual self by normalizing her behavior. D The student uses rationalization to reduce the cognitive dissonance that arises from the discrepancy between her behavior and her parents' expectations.

Answer Key: C To determine how much Pb2+ will precipitate, the student must know the solubility of PbCl2, which is related to the solubility product constant Ksp of PbCl2. Thus, C is the best answer.

A student plans to add HCl to a solution containing Pb(NO3)2(aq). To determine how much Pb2+ will precipitate from solution when the HCl is added, the student needs to know which of the following? _ A Ka for HCl B Ka for HNO3 C Ksp for PbCl2 D Keq for the reaction Pb2+ + 2 e- Pb

Air thus enters the lung as it expands with the thorax. If the thoracic wall is pierced (causing what is known as a sucking chest wound), air enters the pleural cavity. The air pressure inside and outside the lung balance causing the lung to elastically collapse and preventing air intake. The rib cage can still expand (so choice B is incorrect), the diaphragm can still contract (so choice C is incorrect), but the lung cannot be expanded in response, so the correct response is A. Choice D is incorrect because the effect is immediate and it would take some time for the lung to dry and stiffen, if indeed that would happen at all.

A wound that penetrates the rib cage and lets air into the right pleural cavity stops air flow into the right lung because the: _ A lung cannot be expanded. B rib cage cannot be expanded. C diaphragm cannot be lowered. D air dries and stiffens the lung. Answer Key: A Non-forced inspiration occurs when the diaphragm and muscles between the ribs (intercostal muscles) contract. The ribs attached at the sternum and spine lift in what is called a "bucket-handle" motion and the diaphragm flattens. These motions increase the volume of the thoracic cavity. Between the lung and the thoracic wall is a space, the pleural cavity. As the volume of the thoracic cavity increases, atmospheric pressure presses against the inside of the flexible, elastic lung tissue forcing it to conform to the thoracic wall.

Answer Key: C This is a Psychology question that falls under content category "Individual influences on behavior." The answer to this question is C because a drive is an internal state that the individual acts to reduce, which is consistent with the definition of unconscious conflict in the stem. It is a Knowledge of Scientific Concepts and Principles question because it requires applying the definition of drive to the description in the stem.

According to the psychodynamic theory, conflict between the superego and the id leads to unconscious conflict. The ego attempts to reduce this conflict through the use of defense mechanisms. Based on this description, the unconscious conflict functions as: _ A a need. B negative reinforcement. C a drive. D negative punishment.

Answer Key: B Myosin binds to actin during contraction and will remain bound until phosphorylated by ATP. Actin filaments can be "decorated" with portions of the myosin molecule. Although ATP provides energy for muscle contraction, it provides energy for many other cell activities as well and would therefore be nonspecific. In addition, ATP binds to myosin, not to actin, in the contraction cycle. Albumin is a protein found in blood plasma. Myoglobin is the oxygen-binding pigment in muscle. Neither of these molecules is likely to have any specific affinity for actin. Thus, answer choice B is the best answer.

Actin filaments within cells can be identified experimentally by the use of a labeled molecule that binds specifically to actin and not to other cell substances. Which of the following would be best to use as the labeled molecule? _ A ATP B Myosin C Albumin D Myoglobin

Answer Key: D The gall bladder stores bile produced by the liver and secretes it into the small intestine as needed. Bile acts as an emulsifier, facilitating fat digestion. When the gall bladder is removed, a patient will have reduced ability to digest fats.

After the gall bladder is removed from a patient, the patient will most likely have reduced ability to digest: _ A protein. B starch. C sugar. D fat.

Answer Key: D The question asks the examinee to identify the most likely effect of a sharp rise in the level of serum albumen, a major blood osmoregulatory protein. A sharp rise in osmotically active albumin in the serum would increase the flow of interstitial fluid into the bloodstream and result in an increase in blood pressure, not a decrease. Therefore, A is incorrect, and D is correct. B is incorrect because the immune response does not depend on the level of serum albumen. C is incorrect because albumen would not normally pass through capillary walls. Thus, D is the best answer.

Albumin is the major blood osmoregulatory protein. The most likely effect of a sharp rise in the level of serum albumin is: _ A a drop in blood pressure. B an increase in immune response. C an efflux of albumin into the interstitial fluids. D an influx of interstitial fluid into the bloodstream.

Answer Key: B An electrolytic cell drives a non-spontaneous reaction using electrical energy. In the electrolytic cell, electrons are driven in through the cathode and drawn out through the anode. The rate at which this occurs is the current. By increasing the current, electrons are forced in faster, increasing the rate of reduction, and are withdrawn faster thus increasing the rate of oxidation. Answer choice B is the best answer.

An electrolytic cell is designed to produce pure copper from CuSO4. An increase in which of the following cell conditions will most effectively increase the rate at which pure copper is produced? _ A The concentration of SO42+(aq) B The current of electricity C The size of the cathode D The size of the anode

Answer Key: B This is a Psychology question that falls under content category "Social thinking." The answer to this question is B because individuals experiencing self-serving bias attribute their own negative behaviors to situational variables. It is a Knowledge of Scientific Concepts and Principles question because it requires knowing the definition of self-serving bias.

An individual arrives late at a meeting. Which explanation for being tardy is consistent with self-serving bias? The individual will attribute being late to: _ A an uncontrollable personality trait. B a situational variable. C a controllable personality trait. D a stable variable.

The answer to this question is B because phobic responses are usually acquired through classical conditioning. Exposing oneself to the conditioned stimulus (in this case, the confined space) until the conditioned phobia is no longer elicited is consistent with the extinction of a classically conditioned response.

An individual experiences shortness of breath and panic in confined spaces. To overcome this reaction, the individual decides to spend time in a confined space until the shortness of breath and panic response are eliminated. The patient is using which method to eliminate the symptoms? _ A Extinction of an operantly conditioned response B Extinction of a classically conditioned response C Counter conditioning D Aversive conditioning

Answer Key: D Passage of fluid from the blood through the walls of the glomerulus is a passive process and depends mostly on the hydrostatic pressure of the blood in the glomerular capillaries, so answer A is incorrect. The walls of Bowman's capsule do not take part in urine processing, so answer B is incorrect. ADH does not exert its effects on the loop of Henle so C is incorrect. ADH acts on the distal tubule and collecting duct to increase water permeability by the insertion of aquaporins in the plasma membrane. This increases water reabsorption, which reduces urine output, so D is correct.

Antidiuretic hormone (ADH) acts to decrease urine output by increasing the water permeability of the walls of: _ A the glomerulus. B Bowman's capsule. C the loop of Henle. D the distal tubule and collecting duct.

A faraday is equal to one mole of electric charge. Because each aluminum ion gains 3 electrons, 0.1 faraday of charge will reduce 0.1/3 moles of aluminum, or 0.033 moles of aluminum.

Approximately how many moles of Al3+ are reduced when 0.1 faraday of charge passes through a cell during the production of Al? (Note: Assume there is excess Al3+ available and that Al3+ is reduced to Al metal only.) _ A 0.033 mol B 0.050 mol C 0.067 mol D 0.10 mol

Answer Key: A An atomic number represents the number of protons in an atom. As the number of protons increases, the attraction between the nucleus and electrons also increases. In general, more energy is required to remove an electron from an atom for elements on the right than those on the left of the same period of the periodic table due to the greater effective nuclear charge experienced by the former. Thus, A is the best answer.

As atomic number increases in a horizontal row of the periodic table, ionization energy generally: _ A increases, because of increasing effective nuclear charge. B increases, because of increasing atomic radius. C decreases, because of decreasing effective nuclear charge. D decreases, because of increasing atomic radius.

Answer Key: B This is a Psychology question that falls under content category "Making sense of the environment." The answer to this question is B because according to Piaget, an 8-year-old is in the concrete operational stage and cannot engage in hypothetical reasoning, which is not mastered until the formal operational stage. All of the other options describe skills that are mastered by the concrete operational stage. It is a Knowledge of Scientific Concepts and Principles question because it requires knowing the timing of specific cognitive skills based on Piaget's theory.

Based on Piaget's theory of cognitive development, an 8-year-old child's cognition is likely to be characterized by all of the following EXCEPT: _ A symbolic thinking. B hypothetical reasoning. C egocentrism. D conservation of mass.

Answer Key: C Peptides are formed when two amino acid residues are joined through a common amide linkage ("peptide bond"); this bond is formed between the N-terminus of one amino acid residue and the C-terminus of another amino acid residue. Compound X is composed of three amino acid residues linked by two peptide bonds. Thus, answer choice C is the best answer.

Compound X is shown below. Compound X is classified as a: _ A dipeptide that contains one peptide bond. B dipeptide that contains two peptide bonds. C tripeptide that contains two peptide bonds. D tripeptide that contains three peptide bonds.

Answer Key: B The number of different possible gametes that can be formed by diploid organisms as a result of independent assortment of chromosomes during meiosis can be calculated using the formula 2n where n is the haploid number of chromosomes. In this case, the haploid number is 3, making the number of different haploid cells 23, or 8. Thus, B is the best answer.

Consider an organism that has three pairs of chromosomes, AaBbCc, in its diploid cells. How many genotypically different kinds of haploid cells can it produce? _ A 4 B 8 C 16 D 32

Answer Key: B The reaction is second order if the sum of the exponents m and n equals 2. In rate laws, k is the rate constant. The sum of the exponents equals 2 when m equals 1 and n equals 1. Thus, B is the correct answer.

Consider the reaction rate described by the following equation. Rate = k[A]m[B]n The overall reaction is said to be second order when: _ A k is constant, m=0, and n=0. B k is constant, m=1, and n=1. C k is constant, m=2, and n=2. D k=2, and m and n are variable.

Answer Key: D Eukaryotes have membrane-bound organelles including the nucleus, which contains the DNA. Transcription of DNA into RNA occurs in the nucleus. The RNA is then transported to the cytoplasm where ribosomes translate it into proteins. Thus, D is the best answer.

During prokaryotic protein synthesis, translation begins as soon as the newly synthesized mRNA strand begins to extend from the DNA strand. This situation differs from that in eukaryotes, because eukaryotes: _ A carry out translation without using ribosomes. B transcribe mRNA molecules without using DNA. C destroy most mRNA as soon as it is synthesized. D localize the processes of transcription and translation in the nucleus and cytoplasm, respectively.

Answer Key: C In order for an oxidation-reduction reaction to proceed spontaneously, the cell potential Ecell° for the net reaction must be positive. The cell potential Ecell° can be found by subtracting the standard reduction potential Ered° for the substance being oxidized from that of the substance being reduced. The question asks which metals can reduce copper ions. This means that the metals in question are oxidized. The difference in standard reduction potentials Ecell° from the table is positive for lead and zinc but negative for silver. Thus, the correct answer is C.

With which of the above metals can copper form a galvanic cell in which copper is reduced? _ A With silver only B With lead only C With lead and zinc D With silver and zinc While the direct calculation of Ecell° might not show a positive value for Pb and Zn, within the context of a galvanic cell where Cu⁺ reduction is the desired outcome, both Pb and Zn can act as the anode (being oxidized) because their lower E°red values facilitate electron flow towards Cu⁺ for reduction. This ultimately leads to a positive overall Ecell° for the complete reaction in the galvanic cell. Applying the Concepts: Looking at the E°red values provided: Cu⁺: +0.52 V Ag⁺: +0.80 V (higher than Cu⁺) Pb²⁺: -0.13 V (lower than Cu⁺) Zn²⁺: -0.76 V (lower than Cu⁺) Subtracting the E°red of Cu⁺ from each metal's E°red: Ag⁺: (+0.80 V) - (+0.52 V) = +0.28 V (positive) Pb²⁺: (-0.13 V) - (+0.52 V) = -0.65 V (negative) Zn²⁺: (-0.76 V) - (+0.52 V) = -1.28 V (negative) Based on the calculations: The difference (Ecell°) for Ag⁺ is positive, suggesting a non-spontaneous reaction (silver won't reduce Cu⁺). The differences for Pb²⁺ and Zn²⁺ are negative, indicating non-spontaneous reactions on their own. However, in a complete galvanic cell setup, these negative values contribute to a positive overall Ecell° when combined with the positive E°red of Cu⁺ reduction.

Answer Key: B The question asks the examinee to predict the result if chromosomal duplication occurred twice before tetrad formation and all other steps in spermatogenesis occurred normally. If all other steps occur normally, then four sperm would be produced. Because replication occurred twice instead of once prior to tetrad formation, each sperm would have twice the normal amount of DNA. As a result, four diploid sperm would be produced instead of four haploid sperm. A, C, and D are incorrect because they describe results that contain an incorrect number of sperm or ploidy number for the sperm produced. Thus, B is the best answer.

If chromosomal duplication before tetrad formation occurred twice during spermatogenesis, while the other steps of meiosis proceeded normally, which of the following would result from a single spermatocyte? _ A One tetraploid sperm B Four diploid sperm C Four haploid sperm D Eight haploid sperm

Answer Key: B The speed of a wave is given by the product of its frequency times its wavelength: v =fλ. The wave frequency is 1/(3 s); the wavelength is 2 × 1 m because a crest and the adjacent trough are a half wavelength apart. The wave speed is therefore 2 m/3 s = 0.67 m/s. Thus answer B is correct.

If ocean waves strike the shore every 3.0 s and the horizontal distance between adjacent crests and troughs is 1.0 m, what is the average speed of the waves? _ A 0.33 m/s B 0.67 m/s C 1.5 m/s D 3.0 m/s

Answer Key: C The ideal gas law states that PV = nRT. If n (the quantity of gas) is constant and T (temperature) increases, then PV (pressure × volume) will increase. If the pressure remains constant, then the volume must increase. Thus, C is the best answer.

If the quantity of gas remains unchanged while its temperature increases, the volume of the gas will: _ A always increase, because volume is directly proportional to temperature. B always decrease, because volume is inversely proportional to temperature. C increase if pressure remains constant. D decrease if pressure remains constant.

Answer Key: D Pressure is given by (density) • g • (height) if density does not change. This is approximately true for small atmospheric height differences, such as 100 m. The pressure difference will be given by (density) • g • (change in height) or (1.2)(10)(100) = 1200 N/m2. Thus, D is the best answer.

If the second floor and the top floor of a building are separated by a distance of 100 m, what is the approximate difference between the air pressures of the two levels? (Note: Air density = 1.2 kg/m3 and gravitational acceleration = 10 m/s2. Neglect the compressibility of air.) _ A 600 N/m2 B 800 N/m2 C 1000 N/m2 D 1200 N/m2

Answer Key: D The pressure at the bottom of a tube of height h filled with liquid of density r is given by rgh due to the weight of the liquid. This is called hydrostatic pressure. Blood pressure in the arteries between the arm and leg has a pressure difference given by this hydrostatic term, independent of blood flow or viscosity. Choice D is the best answer.

In a healthy person standing at rest, a comparison of arterial blood pressure measured in the arm with that measured in the leg shows that the pressure in the leg is: _ A lower, because the blood flow rate is less. B lower, because viscous flow resistance causes pressure loss. C the same, because viscous pressure loss precisely compensates the hydrostatic pressure increase. D greater, because the column of blood between the arm and the leg has a hydrostatic pressure.

Answer Key: A A nearsighted (myopic) person can focus on nearby objects but cannot clearly see objects far away. The nearsighted eye has a focal length that is shorter than it should be, so the rays from a distant object form a sharp image in front of the retina. This condition is corrected by glasses with a diverging lens. Choice A is the correct answer.

In a nearsighted individual, the image of a distant object is focused: _ A in front of the retina, requiring diverging lens correction. B in front of the retina, requiring converging lens correction. C behind the retina, requiring diverging lens correction. D behind the retina, requiring converging lens correction.

Answer Key: D A substance boils when enough heat has been supplied to overcome the intermolecular forces. The fact that ammonia has a higher boiling point than phosphine indicates that ammonia requires more heat to overcome the intermolecular forces than does phosphine and therefore the intermolecular forces in ammonia are stronger than those in phosphine.

Phosphorus appears directly below nitrogen in the periodic table. The boiling point of ammonia, NH3, is higher than the boiling point of phosphine, PH3, under standard conditions. Which of the following statements best explains the difference in the boiling points of these two compounds? _ A Ammonia is a weaker base than phosphine. B The N-H bond is weaker than the P-H bond. C High molecular weight compounds generally have lower boiling points. D Ammonia forms stronger intermolecular hydrogen bonds than phosphine.

Answer Key: A Endocytosis is the process by which cells engulf extracellular material. Macrophages specialize in this activity. They clear cell and tissue debris and foreign objects from the body, so option A is the correct answer. Erythrocytes specialize in transport of oxygen and do not engage in exocytosis or endocytosis, so option B is incorrect. Osteoblasts form bone tissue. They actively secrete bone matrix, so would not engage in much endocytosis, therefore, answer choice C is incorrect. Neurons secrete neurotransmitter by exocytosis, but do not engage in endocytosis, so answer choice D is also incorrect.

Rates of endocytosis vary from cell type to cell type. What cell would be predicted to have the highest rate of endocytosis? _ A A macrophage B An erythrocyte C An osteoblast D A neuron

Answer Key: C This is a Psychology question that falls under content category "Making sense of the environment." The answer to this question is C because regular breathing and heart rate and slow brain waves are most consistent with deep sleep, NREM3. It is a Knowledge of Scientific Concept and Principles question because it requires knowing the properties of different stages of sleep.

Regular breathing and regular, slow brain waves are most consistent with which stage of sleep? _ A NREM1 B NREM2 C NREM3 D REM

Answer Key: B A plane mirror produces an image behind its plane at a distance equal to the object distance in front of the plane. If the sum between the object and the image distances must be at least 300 cm, then the mirror must be at half this distance, meaning 150 cm.

Suppose a certain far-sighted person can see objects clearly no closer than 300 cm away. What is the minimum distance from a plane mirror such a person must be to see his reflection clearly? _ A 75 cm B 150 cm C 300 cm D 600 cm

Answer Key: B Bernoulli's equation for horizontal fluid flow (when viscosity is neglected) states that the pressure plus kinetic energy density of the fluid is constant. If the fluid velocity falls, the kinetic energy density decreases so the pressure increases. The fluid velocity is lowest where the diameter of the pipe is a maximum. Thus, the pressure is greatest where the diameter is a maximum.

Suppose that a stream of fluid flows steadily through a horizontal pipe of varying cross-sectional diameter. Neglecting viscosity, where is the fluid pressure greatest? _ A At the intake point B At the point of maximum diameter C At the point of minimum diameter D At the point of maximum change in diameter

Answer Key: B ATP must be added. The overall glycolytic pathway yields two ATP molecules, but in order to gain these two ATP molecules by the end of the process, some ATP must be consumed at the beginning. The first reaction, the phosphorylation of glucose, for instance, requires ATP. If this is lacking in the reaction mixture, glycolysis will not be initiated. Once initiated with a small amount of ATP, however, more ATP is produced and the reaction will become self-sufficient. Therefore, the correct answer is option B. Oxygen and acetyl-coenzyme A are needed only for oxidative metabolism, so options A and D are incorrect. NAD is supplied and the process will produce NADH, but NADH is not needed for the reaction sequence to proceed, so option C is incorrect.

Suppose that an extract from a muscle cell contains only the following: all the enzymes of the glycolytic pathway, including the enzyme that converts pyruvate to lactate; phosphate and other salts; NAD+ and ADP. When the extract is incubated anaerobically and glucose is introduced, neither pyruvate nor lactate is produced. What must be added in order for pyruvate to be made? _ A O2 B ATP C NADH D Acetyl-coenzyme A

Answer Key: C The number of individuals carrying the described trait is 480. The gene frequency of the recessive trait, q, can be ascertained by taking the square root of 16/100 or 0.4. Given this frequency, the frequency of p must be 1.0 - 0.4 = 0.6. According to the Hardy-Weinberg law, the frequency of carriers is thus given by 2 pq or 2 X .4 X .6 = .48 or 48%. 48% of 1000 = 480. Thus, answer choice C is the correct answer.

Suppose that in a randomly mating population of mammals, 160 of its 1,000 members exhibit a specific recessive trait that does not affect viability of the individual. How many individuals in this population are heterozygous carriers of the gene that causes this trait? _ A 160 B 400 C 480 D 600

Answer Key: C As secreted proteins, antibodies are translated by ribosomes attached to the rough endoplasmic reticulum. Thus, C is the best answer.

Synthesis of antibody proteins in eukaryotic cells is associated with what organelle? _ A Nucleus B Mitochondrion C Endoplasmic reticulum D Golgi apparatus

Answer Key: A This is a Psychology question that falls under content category "Social thinking." The answer to this question is A because group polarization is a process that affects attitude toward a topic. When people who agree upon a topic are allowed to discuss their attitudes, they tend to become more polarized. It is a Reasoning about the Design and Execution of Research question because it requires identifying the dependent variable of a study based on the concept being tested.

The dependent variable in a study of polarization is most likely to be each participant's: _ A attitude toward a topic. B affinity with the group. C performance on a complex task. D contribution to a group project.

Answer Key: D According to the relation given in the passage, the energy of an electron in orbit n = 3 is less negative or greater than the energy in orbit n = 2. Thus energy is required to make the transition from n = 2 to n = 3 and the atom gains energy. Answer D states precisely this and only D is consistent with this result.

The energy, E, of a hydrogen atom with its electron in the nth shell of a hydrogen atom is given by E = -C/n2 where n = 1,2,3, . . . and C is a positive constant. If an electron goes from the n = 2 shell to the n = 3 shell: _ A a photon is emitted. B an electron is emitted. C an electron is absorbed. D the energy of the atom is increased.

Answer Key: B The reaction equation shows the reduction of H+ by Cd. Because the H+ accepts the electron readily from Cd, it can be determined that H+ has the highest electron affinity.

The following reaction occurs spontaneously.Cd(s) + 2 H+(aq) → Cd2+(aq) + H2(g) Which of the following has the highest electron affinity? _ A Cd(s) B H+(aq) C Cd2+(aq) D H2(g)

Answer Key: D Pipes and tubes have their resonant wavelengths when standing waves develop. An open pipe has its fundamental, resonant wavelength at twice the length of the pipe. Both ends have displacement antinodes (maximum amplitudes) with a node in the middle of the pipe. Thus, the pipe is half a wavelength long. The resonant wavelength is independent of the diameter of the pipe.

The fundamental, resonant wavelength of a pipe open at both ends that is 1 m long and 0.1 m in diameter is: _ A 0.1 m. B 0.2 m. C 1.0 m. D 2.0 m.

Answer Key: C This is a Psychology question that falls under the content category "Making sense of the environment." The answer to this question is C because the graph shows both a primacy effect and a recency effect as exemplified by enhanced free recall performance for items that are at the beginning and end of the list. Primacy effect refers to the improved memory for items that appear earlier in the list and have been encoded into long-term memory. Recency effect refers to the recall of items that are still in short-term memory. For this to occur, recall needs to take place immediately after encoding, when the final items are still held in short-term memory. If retrieval had taken place 20 minutes after encoding, then the recency effect would not have been possible. It is a Data-based and Statistical Reasoning question because it requires reasoning with information from a graph.

The graph shows the results of a study in which participants are asked to recall a list of fifteen words. Which statement is supported by the graph? _ A There is no primacy effect. B There is no recency effect. C Retrieval took place immediately after list presentation. D Retrieval took place 20 minutes after encoding.

Answer Key: B The 18O label will appear at position b in the product. The methoxy group in the product comes from the 18O-labeled methanol. Oxygens at positions a and c in the product come from the unlabeled hemiacetal. Thus, choice B is the best answer.

The hemiacetal below is treated with 18O-labeled methanol (CH3O*H) and acid. Where will the label appear in the products? _ A Position a only B Position b only C Position c only D Positions b and c only

Answer Key: C This is a Psychology question that falls under content category "Making sense of the environment." The answer to this question is C because encoding specificity refers to enhanced memory when testing takes place under the same conditions as learning. It is a Reasoning about the Design and Execution of Research question because it requires identifying the independent variable of a study based on the concept that is being tested.

The independent variable of a memory study that tests the encoding specificity effect is most likely to be: _ A the depth of processing. B the amount of time allowed for encoding. C the location of encoding and retrieval. D the time interval between encoding and retrieval.

Answer Key: C The inorganic component of bone consists of submicroscopic deposits of calcium phosphate similar to hydroxyapatite (Ca10[PO4]6[OH]2), so it would be expected to contain calcium, phosphate and hydroxyl groups. Therefore, the correct answer states that the component not found in the salt is potassium, answer choice C.

The mineral component of human bone is a salt that consists primarily of all of the following EXCEPT: _ A calcium. B phosphate. C potassium. D hydroxyl groups.

Answer Key: A The question asks the examinee to identify the correct order of structures through which sperm cells travel from the male testis to the point of fertilization in the female. As sperm cells leave the testis they travel through the epididymis to the vas deferens and into the urethra. The sperm then enter the female's vagina, travel through the cervix and uterus, and enter the fallopian tube, where fertilization most commonly takes place. Of the options listed, only A correctly identifies both the structures and the order. Thus, A is the best answer.

The normal path of sperm movement from the male testis to the point of fertilization in the female is: _ A epididymis, vas deferens, urethra, vagina, cervix, uterus, fallopian tube. B epididymis, vas deferens, ureter, cervix, uterus, fallopian tube. C epididymis, vas deferens, urethra, vagina, uterus, ovary. D interstitial cells, epididymis, vas deferens, vagina, uterus, ovary.

Answer Key: C The question requires you to identify a major property of sound waves. For sound waves to propagate, there must be a physical medium consisting of atoms that can interact with each other and therefore propagate the perturbation produced by the sound wave. Such medium can be in either solid, liquid, or gaseous state. Recalling one example of each medium is sufficient to determine the correct answer. Thinking that sound waves require large spaces between atoms will lead to answer option A, which is incorrect. Thinking that sound waves require a fluid medium for propagation will lead to option B, which is incorrect. Vacuum means the absence of any atom, hence sound waves cannot propagate through vacuum, thus option D is incorrect.

The properties of sound waves allow them to propagate through: _ A gases only. B liquids and gases only. C solids, liquids, and gases only. D vacuum, solids, liquids, and gases.

Answer Key: C The stem asks which of the organelles listed is associated with the translation of antibody proteins. Of the organelles listed, only the endoplasmic reticulum is associated with translation of proteins. Synthesis is accomplished by the ribosomes, which are associated with the endoplasmic reticulum. The nucleus contains the genetic information, the mitochondria are involved in cellular respiration, and the Golgi apparatus is involved in the processing and/or export of proteins. Therefore, the key is C.

Translation of antibody proteins in eukaryotic cells is associated with what organelle? _ A Nucleus B Mitochondrion C Endoplasmic reticulum D Golgi apparatus

Answer Key: C The difference in pressure in a fluid on Earth is:(density of fluid) × g × (change in height) = (1000)(10)(0.25) = 2500 N/m2. This is answer C.

What is the difference in pressure between two points that are separated by a vertical distance of 0.25 m in a tank of water? (Note: The density of water is 1,000 kg/m3, and g = 10 m/s2.) _ A 250 N/m2 B 400 N/m2 C 2,500 N/m2 D 4,000 N/m2

Answer Key: D Light slows down because the index of refraction in the glass is greater than in the air. The index is a measure of the ratio of the velocity in air to the velocity in the medium. For sound the speed becomes greater because the speed of sound in a solid is much greater than in air (the glass has stiff rigid bonds which gives rise to a speed more than 10 times greater than in air).

When a light wave and a sound wave pass from air to glass, what changes occur in their speeds? _ A Both speed up. B Both slow down. C Light speeds up; sound slows down. D Light slows down; sound speeds up.

Answer Key: D The indicator will change color over a specific pH range. The range at which the color change takes place depends on the point at which HIn is converted to In-, and this depends on the pKa of the indicator which is answer D.

When a weak acid (HA) is titrated with sodium hydroxide in the presence of an indicator (HIn), the pH at which a color change is observed depends on the: _ A final concentration of HA. B final concentration of HIn. C initial concentration of HA. D pKa of HIn.

Answer Key: A An electron has a negative charge and very little mass compared with the charge and mass of nucleons. If an electron is emitted by a nucleus to balance the charge, the nucleus must gain one positive charge (a proton); thus, the atomic number (number of protons in nucleus) increases by one. However, the atomic mass is nearly unchanged because an electron has only 0.05% of a proton's mass. Thus, A is the best answer.

When an element undergoes β decay, a nuclear neutron is converted to a nuclear proton as the nucleus emits an electron. What happens to the atomic number and atomic mass of an element that undergoes β decay? _ A The atomic number increases, but the atomic mass stays approximately the same. B The atomic number stays the same, but the atomic mass decreases. C Both the atomic number and the atomic mass decrease. D The atomic number decreases, but the atomic mass stays approximately the same.

Answer Key: C The question asks the examinee to identify a likely regulatory function of an animal's skin when its muscles contract, causing the animal's hair to stand on end. A major function of hair is to help mammals regulate body temperature by reducing the amount of heat lost to the environment. Hair provides insulation. When the hair stands on end, trapping air within the layer of hair, then its insulating effect becomes even more effective. Thus, as C indicates, a primary function of this action is to help regulate body temperature. The contraction of skin muscles that causes the hair to stand on end would have little effect on skin pH (A), salt excretion (B), or skeletal muscle tone (D). Thus, C is the best answer.

When muscles in the skin contract and cause the hair of an animal to "stand on end," the skin could be functioning as a regulator of: _ A pH. B salt excretion. C body temperature. D skeletal muscle tone.

Answer Key: C This is a Psychology question that falls under content category "Attitude and behavior change." The answer to this question is C because uncontrollable exposure to an aversive stimulus results in learned helplessness, independently of the intensity of the punishment. It is a Knowledge of Scientific Concepts and Principles question because it requires knowledge of the conditions that lead to learned helplessness.

Which experimental procedure is most likely to result in learned helplessness? _ A Giving a participant a very intense electric shock that the participant can escape by pressing a button B Placing a participant in a situation where reinforcement is delivered independently of the participant's responses C Giving a participant a moderate electric shock that the participant cannot escape D Placing a participant in a situation where a response that previously resulted in positive reinforcement no longer does

Answer Key: D This is a Psychology question that falls under content category "Social processes that influence human behavior." The answer to this question is D because social facilitation occurs when an individual completes a manageable task in front of an audience. When an individual works on a challenging task in front of an audience, this might increase arousal beyond optimal and interfere with performance. It is a Scientific Reasoning and Problem Solving question because it requires using the definition of social facilitation and knowledge of the relationship between arousal and performance to identify the correct scenario.

Which experimental scenario is most likely to result in social facilitation? _ A A group of participants, who initially agree on a social issue, are asked to discuss their views with each other B A group of participants, who initially disagree on a social issue, are asked to discuss their views with each other C A participant is asked to solve a complex puzzle in front of other participants D A participant is asked solve an easy puzzle in front of other participants

Answer Key: A If two atoms are isoelectronic, they have the same number of electrons. Neon has ten electrons. F- has 9 + 1 = 10 electrons and so is isoelectronic with Ne. Mg2+ and Na+ have 12 - 2 = 10 and 11 - 1 = 10 electrons respectively. Only He, with two electrons, is not isoelectronic with neon. Answer choice A is the best answer.

Which of the following chemical species is NOT isoelectronic with a neon atom? _ A He B F- C Mg2+ D Na+

Answer Key: C Orbital geometry is also known as electron domain geometry. Hybridization is based on the number of electron domains surrounding an atom. An sp3-hybridized atom, such as C in CH4 or N in :NH3, mixes the s and p subshells (one s and three p orbitals) to form four equivalent orbitals. Four equivalent orbitals point at the vertices of a tetrahedron. Thus, C is the correct answer.

Which of the following describes the orbital geometry of an sp3 hybridized atom? _ A Linear B Trigonal planar C Tetrahedral D Octahedral

Answer Key: B The atomic number of nitrogen is 7. The electrons will begin to fill the lower energy levels first; consequently, the 1s level will fill first with two electrons, followed by 2s with two electrons, and then the 2p level with the last three electrons. The resulting electron configuration is 1s22s22p3. Thus, B is the best answer.

Which of the following electron configurations of nitrogen is the most stable? _ A 1s22s12p4 B 1s22s22p3 C 1s12s22p4 D 1s22s22p23s1

Answer Key: B Electron affinity is a measure of the tendency of an element to gain electrons. It increases from left to right across a row of the periodic table. As the number of valence electrons increases, it becomes easier to achieve a complete octet by gaining electrons, so the elements on the right side of the table, such as oxygen and fluorine, tend to form negative ions. Magnesium, as an alkaline earth metal, tends to give up electrons, forming a positive ion. Of the choices given, fluorine is the farthest toward the right side of the table and has the highest electron affinity. Answer choice B is the correct answer.

Which of the following elements has the highest electron affinity? _ A Carbon B Fluorine C Oxygen D Magnesium

Answer Key: D A structure drawing of benzoin is shown below: Benzoin contains a ketone carbonyl group and an alcohol hydroxyl group. It has no carboxylic acid, ether, or aldehyde. Thus, answer choice D is the best answer.

Which of the following functional groups is found in benzoin, C6H5CH(OH)C(O)C6H5? _ A Carboxylic acid B Ether C Aldehyde D Ketone

Answer Key: B The correct answer is option B, epinephrine. Epinephrine is secreted by the adrenal medulla and its secretion is controlled by the autonomic nervous system. Secretion of the other three hormones is regulated by secretion of anterior pituitary hormones. Cortisone secretion is regulated by adrenocorticotropic hormone (ACTH), progesterone by luteinizing hormone (LH), and thyroxin by thyroid stimulating hormone (TSH).

Which of the following hormones is LEAST directly regulated by the anterior pituitary? _ A Cortisone B Epinephrine C Progesterone D Thyroxin

B

Which of the following is a binocular depth cue? _ A Motion parallax B Retinal disparity C Relative height D Relative size

Answer Key: D Power is defined as the rate of doing work. For the automobile, the power output is the amount of work done (overcoming friction) divided by the length of time in which the work was done. Therefore, answer choice D is the best answer. P = w/t

Which of the following must be known in order to determine the power output of an automobile? _ A Final velocity and height B Mass and amount of work performed C Force exerted and distance of motion D Work performed and elapsed time of work

Answer Key: A The stem asks students to identify the procedure that would be LEAST likely to prevent synthesis of the superantigen. Foils B (binding of the operator), C (binding of the mRNA), and D (insertion of a stop codon) would all be effective ways to prevent synthesis of the superantigen. Adding tRNA nucleotides would be unlikely to prevent synthesis of the antigen. Therefore, the key is A.

Which of the following procedures would be LEAST likely to prevent bacterial synthesis of the superantigen protein? _ A Adding tRNA nucleotides that can bind to mRNA and bacterial ribosomes B Adding a repressor protein that binds to the operator site of the bacterial superantigen gene C Adding a specific complementary nucleic acid sequence that can bind to mRNA transcribed from the superantigen gene D Adding a stop codon within the bacterial superantigen gene

Answer Key: D In insulators, the valence electrons are tightly bound to their atoms, and it takes a great amount of energy to free them from their atomic energy levels. Thus, D is the best answer.

Which of the following statements best characterizes a material that is a good insulator but a poor conductor? _ A The material contains no electrons. B The magnitude of the electric field inside the material is always equal to zero. C The atoms in the material can easily move from one lattice site to another. D Electrons in the material cannot easily move from one atom to another.

Answer Key: B In gastrulation, the three cell regions, or germ layers, are formed in the embryo. From the outer layer (ectoderm) come cells of the nervous system and epidermis, from the inner layer (endoderm) come cells of the lining of the digestive tube and associated organs, and from the middle layer (mesoderm) come the blood cells, connective tissues (bones, muscles, and tendons), and several organs (kidney, heart, gonads). Thus, the eye and spinal cord are formed from ectoderm, the liver is formed from endoderm, and the heart and bone are formed from mesoderm. Answer choice B is the best answer.

Which of the following structures is derived from the same germ cell layer as the heart? _ A Eye B Bone C Spinal cord D Liver

Answer Key: B When an ionic substance dissolves, it dissociates into its constituent ions. The solubility of any substance whose anion is basic will be increased in solutions of low pH, as the basic anion reacts with the H+ in solution and is drawn out of the equilibrium. As the basic anion is consumed, the dissolution reaction is driven to the right by Le Chatelier's principle. Of the substances given as choices, Pb(OH)2 has the most basic anion, OH-. Thus it is most likely to show increased solubility in an HCl solution. Answer choice B is the best choice.

Which of the following substances is most likely to be more soluble in 1.0 M HCl than in 1.0 M NaOH? _ A AgCl B Pb(OH)2 C CaF2 D HI Why Pb(OH)2 is More Soluble in HCl: Pb(OH)2 is a salt with the hydroxide (OH-) ion, which is a strong base. In neutral water, Pb(OH)2 has low solubility due to the equilibrium between the solid and its dissociated ions. When HCl (a strong acid) is added:It dissociates completely, providing a high concentration of H+ ions.OH- ions from Pb(OH)2 react with H+ ions from HCl to form water (H2O). This removes OH- ions from the solution, disrupting the equilibrium for Pb(OH)2 dissociation.To re-establish equilibrium, more Pb(OH)2 needs to dissolve, releasing more OH- ions. This leads to a slight increase in the overall solubility of Pb(OH)2 in HCl compared to pure water. Pb(OH)2, due to the presence of the highly basic OH- ion, exhibits the most significant increase in solubility in an acidic solution (HCl) compared to the other options. This aligns with the common ion effect principle and Le Chatelier's principle, where the equilibrium is driven towards increased solubility to compensate for the removal of OH- ions by H+ ions from HCl.

Answer Key: C The ground state electron configuration of an atom is generally written as follows: 1s22s22p63s23p64s23d104p65s2... with the orbital energetics following the (n + l) rule. When an electron is excited, it "jumps" to a higher energy subshell. Since the 3d subshell (n + l = 5) differs by more than one unit of (n + l) from the 3s subshell (n + l = 3) it is clear that the electron in the 3d subshell is in an "excited" state. Thus, C is the best answer.

Which of the following valence electron configurations corresponds to an atom in an excited state? _ A 1s22s2 B 2s22p1 C 3s23d1 D 4s23d2

Answer Key: D Counting the numbers of atoms of different elements in the structure of caffeine gives the molecular formula, C8H10N4O2. The empirical formula of a compound is the simplest whole-number ratio of the moles of the elements in the compound. Dividing the molecular formula of caffeine by 2 gives the empirical formula, C4H5N2O. Thus, D is the best answer.

Which pair of formulas represents the empirical and molecular formulas, respectively, of caffeine? _ A CHNO and C8H10N2O2 B C4H5N2O and C4H5N2O C C8H10N4O2 and C8H10N4O2 D C4H5N2O and C8H10N4O2

Answer Key: C Work is the product of the force on an object and the distance the object moves in the direction of the applied force. In this case, work = 20 N x 10 m = 200 J. Thus, answer choice C is the best answer.

How much work is done by a constant horizontal 20-N force pushing a 50-kg block a distance of 10 m on a horizontal surface? _ A 50 J B 100 J C 200 J D 500 J

Answer Key: A The ratio of object to image distance equals the ratio of object to image height. The ratio of image to object height is found by rearranging the ratios to give (4f/3)/4f = 1/3. The image is demagnified by a factor of 3. Thus, answer choice A is the best answer.

An object is placed upright on the axis of a thin convex lens at a distance of four focal lengths (4f) from the center of the lens. An inverted image appears at a distance of 4/3f on the other side of the lens. What is the ratio of the height of the image to the height of the object? _ A 1/3 B 3/4 C 4/3 D 3/1 1. Information provided: Object distance (do) = 4f (four focal lengths) Image distance (di) = -4/3f (negative sign indicates inverted image) f = focal length of the lens (assumed to be positive) 2. Using the Lens Equation: The thin lens equation relates the object distance (do), image distance (di), and focal length (f) of a lens: 1/do + 1/di = 1/f 3. Solving for Magnification (m): Magnification (m) is the ratio of the image height (hi) to the object height (ho). We can derive an expression for m using the lens equation: m = -di / do 4. Substituting the values: m = - (-4/3f) / (4f) 5. Simplifying the equation: m = (4/3f) / (4f) m = 1 / 3 Therefore, the ratio of the image height (hi) to the object height (ho) is 1/3. In simpler terms, the image will be one-third the height of the object. 1. Using Magnification (m): As you identified, solving for magnification (m) using the lens equation (m = -di / do) provides a direct ratio between the image and object heights. This is a convenient method because it relates the image and object sizes without requiring additional calculations.

Answer Key: C The buoyant force on an object immersed in a fluid is equal to the weight of the fluid displaced by the object (Archimedes' principle). There were 5 g of liquid displaced; thus, the ratio of object mass to fluid mass is 15/5 = 3. The specific gravity of the object (mass per unit volume compared with water) is three times the specific gravity of benzene (3 x 0.7 = 2.1) because the volumes of object and displaced liquid are equal. Simple Equation: Archimedes' principle Fb = ρf * Vd * g Where: Fb is the buoyant force (Newtons, N) ρf is the density of the fluid (kg/m³) Vd is the volume of the displaced fluid (m³) g is the acceleration due to gravity (approximately 9.81 m/s²)

An object with 15 grams mass is immersed in benzene and suffers an apparent loss of mass of 5 grams. What is the approximate specific gravity of the object? (Data: Specific gravity of benzene = 0.7.) _ A 1.4 B 1.8 C 2.1 D 3.0 The buoyant force is equal to the weight of the displaced benzene. Since the specific gravity of benzene is 0.7 (less than 1), the displaced benzene will weigh less than the object itself. 1. Buoyancy and Archimedes' Principle: When an object is submerged in a fluid, it experiences an upward buoyant force equal to the weight of the fluid displaced by the object. This principle is known as Archimedes' principle. 2. Weight Loss and Displaced Fluid: In this case, the object loses 5 grams of apparent weight upon submersion in benzene. This weight loss signifies the buoyant force acting upwards. The 5 grams of weight loss corresponds to the weight of the displaced benzene. 3. Specific Gravity and Density: Specific gravity is the ratio of an object's density to the density of water (usually taken as 1 g/cm³). Since the specific gravity of benzene is 0.7 (less than 1), the displaced benzene will have a lower density than the object itself. Explanation of the Answer Key: The answer key highlights that the buoyant force equals the weight of the displaced fluid (5 grams). It then calculates the ratio of the object's mass (15 grams) to the displaced fluid mass (5 grams), which is 3. Since the volumes of the object and the displaced fluid are equal (due to Archimedes' principle), the object's density will be 3 times higher than the density of benzene. Finally, it multiplies the specific gravity of benzene (0.7) by 3 to get the approximate specific gravity of the object (2.1). This aligns with the approach we discussed previously.

Answer Key: A Viruses reproduce by replicating within a host cell and thus cannot be said to reproduce by fission, as bacteria do. Many bacteria do have rigid cell walls, but many viruses have rigid capsids, so the presence of a rigid outer covering does not distinguish the two. Neither bacteria nor viruses have a nuclear membrane and both bacteria and viruses can contain RNA and protein. Thus, the best distinction between a bacterium and a virus is reproduction by fission, answer choice A.

An organism is likely to be a bacterium rather than a virus if it: _ A reproduces via fission. B has a rigid outer covering. C lacks a nuclear membrane. D contains both RNA and protein.

Answer Key: B The buoyant force on the solid is the difference between its weight (31.6 N) and its apparent weight in water (19.8 N). This force equals the weight of the water displaced, which, in turn, equals the product of the volume of the solid and the density of water. The specific gravity of the solid, i.e., the ratio of its weight to the weight of an equal volume of water, is then: 31.6/(31.6 -19.8) = 2.68. The correct answer is B.

An unknown solid weighs 31.6 N. When submerged in water, its apparent weight is 19.8 N. What is the specific gravity of the unknown sample? _ A 2.96 B 2.68 C 2.02 D 1.68

Answer Key: D Power transmitted to a load at the user's end of an electrical line is the product of the current I times the voltage V at the user's end. The power company has the option of using a low voltage or a high voltage for a given amount of power delivered. Using Ohm's law (I = V/R), the power delivered can also be written as P = V2/R. The power lost in the transmission line is I2R. Since the resistance R is fixed by the material and dimensions of the line, we see that using a high voltage at a lower current maximizes the power to the user and minimizes the heat loss in the transmission line, choice D.

Electric power for transmission over long distances is "stepped up" to a very high voltage in order: _ A to produce currents of higher density. B to produce higher currents in the transmission wires. C to make less insulation necessary. D to cut down the heat loss in the transmission wires. In long-distance power transmission, the main concern is minimizing energy loss during transmission. This loss occurs primarily due to heat dissipation in the transmission lines. The key concept is resistance. Understanding Resistance and Power Loss: The amount of heat generated in a wire is proportional to the square of the current flowing through it (I^2) and the resistance (R) of the wire, as described by the formula:Heat Loss = I^2 * R Reducing Current for Lower Heat Loss: To minimize heat loss (and energy waste), we can either reduce the current (I) or the resistance (R) of the transmission lines. Challenges of Reducing Resistance: Reducing the resistance of the wires for long-distance transmission becomes impractical. Making thicker wires (lower resistance) would be expensive and difficult to manage. Solution: High Voltage and Lower Current: Instead, we can achieve a significant reduction in current (I) by using a higher voltage (V) for transmission. This relationship is governed by power (P):P = V * I (Power equals voltage multiplied by current) High Voltage, Lower Current, Less Heat Loss: By stepping up the voltage (V) significantly at the beginning of the transmission line, we can achieve the same amount of power (P) using a much lower current (I). This lower current translates to less heat loss (I^2 * R) in the transmission lines.

Answer Key: A Avogadro's law states that equal volumes of different gases at the same temperature and pressure contain the same number of molecules. According to the density values given, 1 liter of gas X weighs 1.44 g and 1 liter of gas Y weighs 1.54 g. Since each sample has the same number of molecules, gas X must have a lower molar mass than gas Y. A lighter molecule diffuses faster than does a heavier one, so gas X diffuses faster than gas Y. Answer choice A is the best choice.

Gas X has a density of 1.44 g/L and gas Y has a density of 1.54 g/L. Which gas diffuses faster? _ A Gas X, because it has a lower molar mass than gas Y B Gas X, because it has a higher molar mass than gas Y C Gas Y, because it has a lower molar mass than gas X D Gas Y, because it has a higher molar mass than gas X

Answer Key: D The question states that HIV is a retrovirus. For the virus to reproduce itself in host cells, its RNA must be converted to DNA, which requires the enzyme reverse transcriptase. Therefore, the key is D.

HIV (human immunodeficiency virus) is a retrovirus, an RNA virus that can insert itself into the human genome. This virus can reproduce in host cells because it contains: _ A enzymes that destroy T cells. B viral DNA that is compatible with human DNA. C core proteins rather than DNA. D reverse transcriptase.

Answer Key: C The relation between distance, acceleration, and time is: d = (1/2)a • t2. To solve for the time it takes the runner to use t = (2d/a)1/2 = (2 • 3/1.5)1/2 = 2 s. Therefore, answer choice C is the best answer.

How long will it take a runner, starting from rest and accelerating uniformly at 1.5 m/s2, to travel 3.0 m? _ A 2 1/2 sec B 1.5 sec C 2.0 sec D 3.0 sec

Answer Key: D Based on the given information, the tall pink plant would have the genotype TtRr and could form the following gametes: TR, Tr, tR, and tr. The short pink plant would have the genotype ttRr and could form the following gametes: tR and tr. The possible genotypes of the offspring are displayed in the following Punnett square. Of these, 1/4 would be both pink (Rr) and tall (TT or Tt). Thus, D is the best answer.

In a particular species of plant, tall vine depends on a dominant gene (T), and a pink flower is the result of the heterozygous condition of the genes for red and white flowers (Rr). What fraction of the offspring from the cross of a tall, pink plant (heterozygous for height) with a short, pink plant would be expected to be pink AND tall? _ A 3/4 B 1/2 C 3/8 D 1/4 Understanding the scenario: Genes and Traits:In this plant species:Height: Determined by a single gene with two alleles - Tall (dominant - T) and Short (recessive - t).Flower Color: Determined by two genes with incomplete dominance.Red flower (R) and White flower (r) alleles combine to produce pink flowers in heterozygous condition (Rr). Parent Plants:Tall, pink plant (TtRr): This plant is heterozygous for both height (Tt) and flower color (Rr).Short, pink plant (ttRr): This plant has the recessive allele for height (tt) but is also heterozygous for flower color (Rr). Question: Proportion of Pink and Tall Offspring The question asks for the expected fraction of offspring from this cross that would be both pink and tall. To determine this, we need to perform a Punnett Square analysis considering both genes and their alleles.

Answer Key: C In horses, the genes for red coat color and white coat color are codominant. Heterozygous horses have roan-colored coats. If a roan-colored colt (CRCW) has a white mother (CWCW), the father's coat must be either roan (CRCW) or red (CRCR). The mother could only give the white color gene, so the father must have given the red. For the father to give the red color gene, he would have to carry one or two copies of it, meaning he must be either red or roan, respectively. Thus, C is the best answer.

In horses, the genes for red coat color and for white coat color are codominant. Heterozygous horses have roan-colored coats. Consider a roan-colored colt that has a white mother. What could be said about the coat color of the colt's father? _ A It must be red. B It must be roan. C It could be either red or roan. D It could be either red or white. The father is also roan (heterozygous for red and white): In codominant inheritance, both alleles for coat color (red and white) are fully expressed in heterozygous individuals, resulting in a roan coat. If the mother is white (homozygous for white) and the colt is roan, the father must have contributed a red allele to get the roan phenotype. The father is red: If the mother is white (ww) and the colt is roan (rw), the father could be red (rr) and contribute the red allele (r) to the offspring.

Answer Key: B This is a Psychology question that falls under content category "Social processes that influence human behavior." The answer to this question is B because studies on bystander intervention show that the more bystanders there are, the longer it takes for an individual bystander to offer help. It is a Data-based and Statistical Reasoning question because it requires reasoning about the direction of correlations.

In studies of bystander intervention, which variable is typically found to be positively correlated with the time it takes for an individual to offer help in case of emergency? _ A The severity of the emergency B The number of bystanders who witness the emergency C The individual's level of altruism as assessed by a standardized measure D The degree to which altruism is a part of the individual's self-image

Answer Key: B Currents in parallel resistors are inversely proportional to their individual resistances because they have the same voltage drop across them (Ohm's law). Since the 2 ohm resistor in the diagram has 2 A, the parallel 4 ohm resistor has 1 A through it. These currents add to 3 A as they combine to pass through the 3 ohm resistor (Kirchhoff's junction rule). If the 2-ohm and 4-ohm resistors are indeed in parallel, then with a current of 2 A in the 2-ohm resistor, the current in the 4-ohm resistor would be less than 2 A (due to the inverse proportionality).

In the circuit shown above, the current in the 2-ohm resistance is 2 A. What is the current in the 3-ohm resistance? _ A 2 A B 3 A C 4 A D 6 A

Answer Key: A The knee-jerk reflex is a simple monosynaptic stretch reflex. A tap to the tendon that connects the quadriceps to the patella activates a sensory neuron that directly synapses with a motor neuron in the spinal cord, causing the quadriceps to contract. Thus, A is the best answer. Associative neurons are found in the brain and help with complex information processing. They are not directly involved in the simple reflex arc of the knee-jerk reflex.

In the human "knee-jerk" reflex, the knee is struck and the lower leg jerks forward. Which of the following represents the complete pathway that the nerve impulse travels in effecting this response? _ A Sensory neuron, motor neuron B Sensory neuron, brain, motor neuron C Sensory neuron, associative neuron, brain, associative neuron, motor neuron D Sensory neuron, associative neuron, motor neuron, associative neuron, motor neuron

Answer Key: C The speed of sound is greatest by far in a solid because of the strong intermolecular bonds and close proximity of the molecules. Because the temperatures are close to each other (and even favor iron slightly), iron will have the highest sound speed. Thus, C is the best answer.

In which of the following does sound travel most rapidly? _ A Air (0°C) B Water (10°C) C Iron (20°C) D Sound travels at approximately the same speed in all of the above.