General MCAT Chem/Phys I keep missing

The most effective method for producing an increase in the total amount of water lost through the skin during a certain period would be:

Water is lost through the skin primarily as a means to keep the body at normal temperatures. Therefore, raising the environmental temperature would cause a person to perspire, releasing water to the environment where it can evaporate and cool down the body. Thus, D is the best answer.

SEE BACK FOR QUESTION Answer is as follows First step is to identify what kind of reaction this is First order there for units of rate constant are 1/sec The protein unfolds by a unimolecular mechanism. The rate of unfolding has units of M/s and is given by the expression Δ[unfolded protein length]/Δt = ku[folded protein length]. The units of ku are therefore s-1.

What are the units for the rate constant ku discussed in the passage? Not this passage is about protein folding as a reaction

The answer to this question is C because there is a higher percentage of Compound 4a than Compound 4b at equilibrium (a thermodynamic mixture). For a thermodynamic mixture of isomeric products, the relative mole ratio of products is directly related to the relative stability of these products.

What can be inferred from the results of Scheme A about the relative thermodynamic stabilities of Compounds 4a and 4b? A. They are equally stable. B. Compound 4a is less stable than Compound 4b. C. Compound 4a is more stable than Compound 4b. D. Nothing can be inferred about relative thermodynamic stabilities.

It is just like a titration curve except with x and y swapped!

What does this graph remind you of

READ BETTER Turn concentration into fraction then take the inverse of that!

What is the KM of Compound 1 with respect to lactase?

The answer to this question is A because the E147D variant is fairly conservative, with both side chains being negatively charged. Aspartate has a slightly shorter chain and thus will be further from the active site. Since the resulting enzyme shows very low conformational stability, the best explanation is that a repulsive interaction develops that reduces conformational stability which eliminates the possibility of catalysis.

What is the best explanation for the observed behavior of the E147D variant? The substitution results in:

The answer to this question is C because a hydroxamic acid was described in the passage as resulting from the acetylation (attachment of RC=O) of the hydroxylamine nitrogen (NHOH) in Compound 2. Only Response C fits this description.

What is the general structure of a hydroxamic acid?

Final Answer: Power at constant speed is related to the applied force as P = F × v. From Figure 3, P = 75 pN × 1000 nm/s = 7.5 × 10-17 W.

What is the mechanical power exerted on the protein when the retraction speed is 1000 nm/s?

This one question is going to make me need even more therapy Answer: 0 Appropriate means the energy is exactly equal to the energy required to break the bonds. "appropriate laser" was supposed to mean 100% efficiency This is a Physics question that falls under the content category "Translational motion, forces, work, energy, and equilibrium in living systems." The answer to this question is D because the energy in the photochemical reaction ΔHu is the difference between the laser pulse energy Em and the heat detected ΔHnr, so the reading of the energy meter is the energy that is neither ΔHu nor ΔHnr. Based on the energy conservation, this is equal to zero for a laser used to dissociate a particular chemical bond. It is a Reasoning about the Design and Execution of Research question because you must reason about the appropriateness of tools that are used to conduct natural sciences research.

What is the reading of the energy meter in Figure 1 when an appropriate laser is used in PAC to dissociate a particular chemical bond?

A gas that occupies 10 L at 1 atm and 25oC will occupy what volume at 500 atm and 25oC?

somewhat more than .02 because of space occupied by individual gas molecules 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.

Which alcohol will most likely undergo substitution by an SN1 mechanism in acidic conditions?

tertiary because carbocation forms!!!!

Standard conditions is what and what is it used for?

used for thermodynamics problems, and it is 298K, 1 atm pressure, 1 M concentrations of all compounds.

power in a circuit (equation)

P = IV = I^2R = V^2/R

When the stopcock is opened, how far up the tube will the water rise? A. 1 m B. 5 m C. 10 m D. 20 m

P=pgh solve for h answer is 10

strontium- symbol on periodic table

Sr

What is this questions really asking .... "Which of the following statements is consistent with the incorrect conclusion that HCl is an ionic compound?"

"Which of these features is something that applies to an iconic compound?"

As the pressure applied to a sample of water at -0.1°C is increased from 1.0 torr to 200 atm at constant temperature, the:

1. Here, the first set of conditions is -0.1°C temperature and 1.0 torr pressure. One can find this initial condition where the 1.0 torr pressure line (the bottom horizontal dashed line) crosses the -0.1°C temperature line (somewhere between the two dashed vertical lines on the graph). This point lies in the vapor region, so the sample begins as a vapor. 2. Due to the negative slope as pressure increases from the intial point it will become a solid first 3. As you increase pressure even more (off the graph) it will resort back to a liquid

A stationary receiver detects a change in frequency of the signal from a jet flying directly away from it at 300 m/s. Which of the following receivers will detect the same change in frequency from a jet moving away at 600 m/s?

600-300m/s=300m/s with respect to the stationairy reciever

What is the spacing between adjacent nodes in a standing-wave pattern?

A half wavelength has a node at each end. The spacing between nodes is λ/2. Therefore D is the correct answer.

Human speech is generated in the vocal cords as the lungs push air past them. What property of the vocal cords is changed so that the frequency of sound can be altered?

A change in the volume of the vocal cords cannot affect the sound frequency because the frequency only depends on the propagation speed (for a fixed-length cord), and the speed is independent of the volume. A change in the density of the vocal cords cannot affect the sound frequency because the frequency only depends on the propagation speed (for a fixed-length cord), and the speed is independent of the density, as it propagates as a transverse wave through the cords. The frequency of the sound produced in vibrating cords and strings (such as vocal cords) of fixed length is proportional to the propagation speed of the sound through the cord. In turn, the propagation speed of a transverse wave (such as the sound wave in the vocal cords) is directly proportional to the tension applied along the cord. The number of vocal cords used in generating the speech is constant.

Visible light travels more slowly through an optically dense medium than through a vacuum. A possible explanation for this could be that the light:

A is known to occur and is the reason for the slowing down of light. B is incorrect because the nucleus is involved. C is incorrect because the motion of the photons is certainly not random. D is true but does not answer the question. Thus, A is the best answer.

Assume that the density of Ball 1 is 8.0 × 102 kg/m3. Ignoring the atmospheric pressure, what fraction of Ball 1 is above the surface of the water?

According to Archimedes' Principle (AP) the upward buoyant force, B, on the ball equals the weight of water displaced by the ball. The mass of displaced water would be ρVS, so the weight of displaced water would be ρVSg. The ball floats, so its weight mg is balanced by the upward buoyant force, thus ρVSg = mg. The ball's mass is D1V, hence ρVSg = D1Vg which may be solved for the submerged volume: VS = (D1/ρ)V = (800/1000)V = 0.8V. This tells us that 0.8V is below the surface, thus V - 0.8V = 0.2V must be above the surface. The fraction of ball 1 above the surface is thus 2/10 = 1/5. Thus, D is the best answer. pVsg=Mball*g Solve for Vs which leads to the specific gravity equation object density/density of the fluid it is = fraction of volume submerged 1-volume submerged gives you volume above surface

During what time period of the freeze-thaw episode shown in Figure 1 were the frog's tissues relying entirely on anaerobic respiration? (Graphs show Body Temp, Heart Rate, ice Content, Tissue Glucose, Tissue Water) which are most relavent for anaerobic respiration?

According to Figure 1, the heart rate was 0 between 12 and 26 hours after the onset of freezing. During that period the heart was not circulating oxygenated blood to the tissues so the cells would have had to rely entirely on anaerobic respiratory mechanisms for energy. Recall that anaerobic metabolic pathways can produce energy without using oxygen by glycolysis. Before 0 hours, the freeze-thaw episode had not begun. From 0 to 12 hours the heart rate indicates that oxyhemoglobin was being circulated in the blood for oxidative metabolism by the cells, so that anaerobic respiration would have been unnecessary. Thus, answer choice D is the best answer.

Answer P=E/time

According to the data in Table 1, what is one of the values of the electromagnetic energy delivered during one pulse by the ionizing radiation?

What is the combined focal length if the sum of focal lengths for two lenses equals the distance between them?

Afocal System aka a simple optical telescope an afocal system produces no net convergence or divergence of the beam

According to trends in electronegativity, which of the following pairs of atoms is most likely to form an ionic bond?

An ionic bond is most likely to form between elements of very high and very low electronegativity. In practice this generally means elements at the far right and far left of the periodic table respectively. Of the pairs of elements offered as choices, only calcium and iodine are found at opposite sides of the periodic table. An ionic compound of formula CaI2 is likely to form between them.

Remember to always refer to periodic table even when given graphs/tables in the passage. Which of the following has the most ionic character? KBr CsCl NaI RbBr

Answer CsCl

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?

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.

To keep the current constant during the discharge cycle:

As the capacitor discharges the voltage across it falls, thus to maintain a constant current, R must be proportionately reduced. This is so from Ohm's law, I = V/R. To keep I fixed, R must fall with V. This is answer B.

What is the magnitude of the detected sound frequency shift from 170 Hz during the projectile flight described in the passage?

As the object moves up and slows down, the frequency shift is negative and falls to zero at the peak of the object's flight; as the object falls, the shift becomes increasingly positive. However, to find the magnitude of the frequency shift from 170 Hz, the negative or positive sign of the shift can be ignored and only the absolute value matters. Thus, A is the best answer.

When are deviations from the ideal gas law observed?

At low pressure or high-temperature conditions, gas mixtures can be considered ideal gas mixtures for ease of calculation. When systems are not at low pressures or high temperatures, the gas particles are able to interact with one another; these interactions greatly inhibit the Ideal Gas Law's accuracy.

The complement to the WT sequence does NOT contain which nucleoside? 5′-TTCCCTACCCTCCCCACCCTAA-3′ A. Deoxyadenosine B. Deoxycytidine C. Deoxyguanosine D. Deoxythymidine

B

Correct answer A

Based on the passage, what is the structure of the product of the reaction between 8-hydroxyquinoline-5 sulfonate and HRP?

Projectile Motion: An object in projectile motion emitting a sound. The wavelength of the detected sound when the projectile is at h is:

Because the projectile has stopped moving, there is no Doppler shift. The wavelength is λ = vsound/f = 340/170 = 2 m. Thus, C is the best answer.

Assume that the side of the water tank is punctured 5.0 m below the top of the water, and that atmospheric pressure is 1.0 × 105 N/m2. What is the approximate speed of the water flowing from the hole?

Bernoulli's equation: P2 + ½ ρv22 + ρgy2 = P1 + ½ ρv12 + ρgy1. Take point 2 to be at the location of the puncture and point 1 to be at the upper surface of the fluid. Also note that the speed of water exiting the small puncture will be much larger than the speed of the upper water level falling at point 1. Thus, v2 >>v1 and v1 may be ignored. Canceling the pressures and setting v1 = 0 leaves the approximate result: ½ ρv22 + ρgy2 = ρgy1, v2 = [2g(y1 - y2)]1/2. The examinee is given that the height difference y1 - y2 is 5.0 m, hence, v2 = [2 (9.8 m/s2) (5.0 m)]1/2 = [98 m2/s2]1/2 ≈ 10 m/s. Thus, A is the best answer.

The 14C atom undergoes beta decay to 14N. What particle is being emitted from the carbon nucleus? ALSO Note the passage said this: "The mass of the beta particle is 9 × 10-31 kg. The velocity of electromagnetic radiation in vacuum is 3 × 108 m/s. Planck's constant is 6.6 × 10-34 J·s."

Beta decay is the emission of an electron or a positron. The atomic number Z changes from 6 for carbon to 7 for nitrogen. Therefore a negative charge must have been emitted by carbon. Of all the particles mentioned, only the electron has a negative charge. The correct answer is A.

If some but not all of the offspring from repeated matings of the same pair of fruit flies show the recessive traits of vestigial wings (vv) and ebony color (ee), which of the following could have been the genotypes of the individuals mated?

Both VvEe

What functional group does CHO indicate?

CHO= aldehyde/carbonyl

Polarity of main functional groups (8ish groups) generally a functional group is more polar if it has more H-Bond acceptors (aka lone pairs on FON)

COOH > Amide > Alcohol > Amine > Aldehyde/Ketone > Ester > Ether > Alkane

Researchers change the value of R and record the reading of the ammeter each time. The value of V can best be determined from which of the following? The slope of a graph of current as a function of R B. The slope of a graph of current as a function of 1/R C. The y-intercept of a graph of current as a function of R D. The y-intercept of a graph of current as a function of 1/R

Correct answer is B Note that Y-intercept gives you the y axis value when the slope is equal to zero

A 0.5-kg uniform meter stick is suspended by a single string at the 30-cm mark. A 0.2-kg mass hangs at the 80 cm mark. What mass hung at the 10-cm mark will produce equilibrium?

Correct answer is m-1kg Thus, the torque left of the suspension will be mg(20 cm). There are two torques right of the suspension, the hanging mass torque (0.2 kg)g(50 cm) and the weight of the meter stick's torque (0.5 kg)g(20 cm), where 20 cm represents the distance from the suspension to the center of mass of the meter stick. Thus, the net right torque is (0.2 kg)g(50 cm) + (0.5 kg)g(20 cm). Equating the left and right net torques yields m = 1 kg. Thus, D is the best answer.

What elements are covalent network solids in their standard state?

Covalent Network Solids are giant covalent substances like diamond, graphite and silicon dioxide (silicon(IV) oxide)

The converging lens in Figure 1 is removed and the diverging lens is placed in position B, as shown in the figure below. Which of the following best describes the light rays from the diverging lens in this configuration?

Each light ray will refract at each surface of the lens and will increasingly diverge from the others because of the shape of each surface, so only diverging rays can result.

Approximately how much Al2O3 is required to make 100 kg of Al? A

Equation 4 shows that 4 mol Al is produced from 2 mol Al2O3. 100,000 g Al × (1 mol Al/27 g Al) × (2 mol Al2O3/4 mol Al) × (102 g/mol Al2O3) = 188.9 kg Al2O3

Snells law relationship of angle of incidence to angle of refraction

Explanation: As the angle of incidence increases, the angle of refraction also increases proportionally to the increase of incidence

If the speed of the charged particle described in the passage is increased by a factor of 2, the electrical force on the particle will:

F=qE does not depend on speed Note Fnet= ma (acceleration only depends on change in velocity or speed) if speed is increasing by factor of 2 then any change in speed is also increasing by factor of 2 so there is not change

What is the oxidation number of aluminum in Na[Al(OH)4](aq)?

First break down Na has a charge of +1 There fore Al(OH4) has a charge of -1 OH has a charge of -1 so Al must be +3

A researcher measures the initial rate (V0 = Δ[P]/Δt) of an enzymatically catalyzed reaction at a variety of substrate concentrations [S]0. Which graph best represents the observed relationship between [S]0 versus V0?

For enzymatically catalyzed processes, the reaction rate will level off with increasing concentration of substrate as the enzyme becomes the bottleneck for the reaction. This is called saturation kinetics. Unlike first-order processes, increasing the concentration of substrate will not linearly increase the rate. Unlike second- or third-order processes, where increasing the substrate concentration can cause a squaring or tripling of the initial rate, enzymatically catalyzed reactions will not show such increases. In general, increasing the concentration of a reactant will increase the rate of its reaction.

The boiling point of glycerine in comparison with that of isopropyl alcohol, (CH3)2CHOH, is:

Glycerine (also known as glycerol) contains three hydroxyl groups, each capable of participating in hydrogen bonds. Isopropyl alcohol contains only one hydroxyl group. Glycerine is expected to be much more extensively hydrogen bonded than isopropyl alcohol. As hydrogen bonding increases the boiling point of a liquid, glycerine has a significantly higher boiling point than does isopropyl alcohol.

What is the half equivalence point?

Half Equivalence Point The half equivalence point represents the point at which exactly half of the acid in the buffer solution has reacted with the titrant. The half equivalence point is relatively easy to determine because at the half equivalence point, the pKa of the acid is equal to the pH of the solution.

The answer to this question is D. By consulting Figure 1 it can be estimated that liposomes with a diameter of 250 nm will elute at approximately 7.5 mL under size exclusion chromatography conditions used in the passage. Using the data presented in Figure 1, this means that a concentration larger than 0.20 mM must be employed in their synthesis. It is a Data-based and Statistical Reasoning question because you are asked to analyze and interpret data presented within the context of an experiment to arrive at the conclusion.

How can use use the graph and table in this problem?

A scientist proposed that the 32P label was entering PE molecules by direct exchange (swapping phosphate groups with those found in solution) and NOT through synthesis of new PE by bacterial cells. What experimental modification can show this is NOT the case? WHAT IS THS QUESTION REALLY ASKING?

How do we test acellular PE production compared to cellular production via bacteria? This would result in no incorporation of the labeled 32P. The rates of bacterial PE synthesis and any potential phosphate exchange should be different. Also, it is unlikely that phosphate would exchange from a phospholipid. This change is not relevant to the issue cited in the stem. If the enzyme responsible for PE synthesis is not saturated with PO43- this will result in slower incorporation regardless of the mechanism by which it takes place.

Passage States: These sulfur bacteria consumed sulfate ions in seawater and excreted the weak acid H2S, as shown in Equation 1. SO42-(aq) + 2 H+(aq) + 4 H2(g) → H2S(aq) + 4 H2O(l) To a first approximation, the ionization constant of H2S is: A. less than zero B. Between 0 and one but closer to zero C. Between 0 and one but closer to zero D. Greater than one

If it is a weak acid Ka is positive but closer to zero "The value of the ionization constant is therefore somewhere between 0 and 1, but much closer to 0." NOTE:As an example, phosphoric acid, among the strongest of the weak acids, has an ionization constant that is approximately 1 x 10^-2, or 0.01. This is much closer to 0 than 1.

Suppose that a ball is thrown vertically upward from earth with velocity v, and returns to its original height in a time t. If the value of g were reduced to g/6 (as on the moon), then t would:

If you throw an object straight up vi=-vf You could also use vf = vi + at (we know vf = -vi, so vi = v & vf = -v. Also a = g) -v = v + gt -2v = gt -2v/g = t There fore decreasing g by 1/6 would increase t by 6

When an initially heterozygous macronucleus undergoes repeated binary fission, the result will be:

In the passage it states that the macronucleus is 45-ploid. If haploid cells have one copy of each chromosome and diploid cells have two copies of each chromosome, then one can infer that 45-ploid cells have 45 copies of each chromosome. Polyploidy, having more than two copies of each chromosome, is unusual in animals, but important in plants and microorganisms like Tetrahymena. The amitotic division of the macronucleus will result in uneven distribution of chromosomes, hence an unpredictable genome. Answer D is therefore correct; the allele distribution will be uneven. Given the large numbers of identical chromosomes in the macronucleus, however, repeated divisions are unlikely to result in the loss of a chromosome, so choice A is incorrect. There is no crossing over in the production of a macronucleus, because the phenomenon of crossing over is a very complex and specialized event that occurs only when meiosis will be taking place, so B is incorrect. C is incorrect because all macronuclei trace their origin ultimately to their micronucleus.

Al(OH)3(aq) + NaOH(aq) → Na[Al(OH)4](aq) In the reaction shown in Equation 1, Al(OH)3 acts as what kind of acid or base? Lewis acid Lewis base Brønsted acid Brønsted base

In the reaction shown in Equation 1, the Al in Al(OH)3 accepts an electron pair from the OH- of NaOH and is therefore acting as a Lewis acid. Thus, A is the best answer.

How will W change if the angle of the ramp to the horizontal is increased?

Increasing height decreases normal force 'The examinee must determine the effect that increasing the ramp's angle will have on the work done by the friction, W, on the mass. The definition of the work of a force is W = Fdcosθ, where F is the magnitude of the force, d is the distance traveled, and θ is the angle between the force and the displacement. Kinetic friction F acts up the ramp and d is down the ramp, so θ= 180°, hence W = −Fd. The kinetic friction force F is the product of the normal force N that the ramp exerts on the mass and the coefficient of kinetic friction μkh. Thus W = − μkhNd. Increasing the tilt of the ramp has no effect on d or μkh, but it does decrease normal force N. For a very steep ramp, the mass is nearly in free fall and pushes down on the ramp very little, hence N is small. Therefore, W decreases when the ramp's tilt is increased. Thus, A is the best answer.

Inflation of the lungs in mammals is accomplished by:

Inflation of lungs in mammals is accomplished by negative pressure pumping action. Because the lung stays in contact with the thoracic wall as it enlarges due to contraction of the diaphragm and the external intercostal muscles, a pressure that is lower than atmospheric pressure (negative pressure) is generated within the alveolar sacs. Although diffusion of gases is important in the movement of oxygen into the blood from the alveoli and the movement of carbon dioxide out of the blood into the alveoli, it does not explain the inflation of the lung alveoli at inspiration. Active transport describes a situation in which the net movement of a substance occurs against the energy gradient. Thus, answer choice D is the best answer.

Which compound with have the lower boiling point? One with intramolecular hydrogen bonding vs. intermolecular hydrogenbonding? One with multiple hydrogen bonds vs. one hydogen bond pair?

Intramolecular will have lower boiling point.

Which of the following properties is most useful in explaining the trend in the reactivities in Experiment 1? Passage is about experiments measuring the reactivity metals EN Ionization Potential Electron Affinity Polarizability

Ionization Potential most relevant because metals loose electrons (they don't gain them) The metals that reacted in Experiment 1 underwent oxidation. The energy required to remove an electron from an atom is the ionization potential. The reactivity of a metal depends on its ionization potential. Among the metals listed in Table 1, potassium has the smallest ionization potential and magnesium has the largest ionization potential. Therefore, potassium reacted the most vigorously and there was no obvious reaction with magnesium.

After a block began to slide, how did its speed vary with time? (Note: Assume that the tension and kinetic friction forces on the block were constant in magnitude.)

It increased linearly with time! The coefficient of kinetic friction is always lower than that of static friction. Therefore there is a net accelerating force on the block once it starts to slide. A constant force on a mass produces a constant acceleration (Newton's second law). Thus, the velocity of the block increases linearly with time.

The term "ideal gas" refers to a gas for which certain assumptions have been made. Which one of the following assumptions applies to an ideal gas?

It is assumed that the molecules in an ideal gas have no volume and that there are no interactions between the molecules. No interactions means that collisions are fully elastic (there is no intermolecular forces messing with Kinetic energy of the gas molecules) Note that STP conditions is not a requirement/assumption of ideal gas law!

Solving inverse trig functions

Just knowing the common sin(x) values (0, 30, 45, 90 etc) can help a lot with that. For example: sin-1 (1/3) = 19.5 degrees Of course you in the mcat you would arrive to this answer through estimation. we know sin(0 degrees) = 0 and sin(30 degrees) = 1/2 So we know our critical angle should be between 0 degrees and 30 degrees but something closer to 30 considering the fact that 1/2 is closer to 1/3 than it is to 0.

Suppose that a blood vessel of cross-sectional area A carries microbubbles at a speed v into a capillary bed. If the capillary bed is made up of n capillaries, each with cross-sectional area a, with what speed will the blood flow in the capillary bed?

Keep it simple Av1=A2v2 solve for v2 Correct answer B

Always remember to convert your temperature to

Kelvins. The only time this doesn't matter is if you have a delta T, since the size of a Kelvin is the same as the size of a Celsius degree and you are taking the difference in that case. But if there isn't a delta, you must convert to K.

The lipases catalyze the hydrolysis of fats and other carboxylic acid esters. The lipases illustrate the fact that:

Lipases catalyze the hydrolysis of fats and other carboxylic esters—similar to fats, but not fats. Lipase's ability to catalyze the hydrolysis of fats and similar molecules reveals that some enzymes interact with several different substrate molecules that have similar chemical linkages.

Which of the following best describes the motion of a negatively charged particle after it has been injected between the plates of a charged, parallel-plate capacitor? (Note: Assume that the area between the plates is a vacuum.)

Opposites attract, so the negatively charged particle will move toward the positive plate. Because there is a constant force qE on the particle, it will accelerate toward the positive plate. Thus, C is the best answer.

A sparingly soluble metal hydroxide, M(OH)2 has a molar solubility of S mol/L at 25°C. Its Ksp value is:

M(OH2)=> M + 2OH starts off probably as solid so don't include that in Ksp ALWAYS include Molar coeffecients in KSP AND any Keq [S]* [2S]^2 The Ksp for a substance, AaBb, equals [A]a[B]b. The Ksp for M(OH)2 = [M][OH-]2. If the solubility of M(OH)2 is S mol/L, then [M] = S mol/L and [OH-] = 2S mol/L. The Ksp = S(2S)2 = S(4S2) = 4S3. Thus, D is the best answer.

A student has a thin copper beaker containing 100 g of a pure metal in the solid state. The metal is at 215°C, its exact melting temperature. If the student lights a Bunsen burner and holds it for a fraction of a second under the beaker, what will happen to the metal?

Melting occurs at a constant temperature because a certain amount of energy, the latent heat of fusion, is needed to convert a substance from its solid to liquid state. The temperature of the metal will not increase above its melting point until all of the metal has melted. The small amount of heat supplied by the bunsen burner is insufficient to melt 100 g of the metal but could melt a small amount of the metal at the constant temperature of the melting point. Thus, answer choice A is the best answer.

How many moles of KHP are present in the sample of KHP of student A? Note: KHP (potassium acid phthalate, MM = 204.2)

Moles= mass you have/MM

What is the general polarity of organic chemistry compounds? What can you use this information to gauge?

More polar compounds will have more intermolcular bonding which will raise boiling point This is especially relvenat for separating compounds

The structure and bonding of diamond, which is formed from graphite at extreme pressures, should be similar to that of elemental:

Note Graphite/Diamonds are made of Carbon (remember that elements in the same column exhibit similar chemical behaviors).

At which electrode is aluminum produced in a galvanic cell and in an electrolytic cell?

Note that Aluminum production implies the production of solid Alumnium! (Solid aluminum implies nuetral charge Al) which indicates a reduction half reaction occured. Reduction ALWAYS happens at the the cathode no matter what cell type!

A ray of light in air strikes the flat surface of a liquid, resulting in a reflected ray and a refracted ray. If the angle of reflection is known, what additional information is needed in order to determine the relative refractive index of the liquid compared to air?

Number 1 Tip is draw it out quick! To find the relative refractive index to air one needs both the incident and refracted angles. nairsin0= n2sin0 When light is reflected angle of incidence =angle of reflection (Law of reflection!) Snell's law. n1sinθ1 = n2sinθ2 so n2/n1 = sinθ1/sinθ2, and since θ1 can be calculated from the angle of reflection, you only need θ2 the angle of refraction to determine n2/n1 (B)

Alternatively, the fertilizer ammonium monohydrogen phosphate [(NH4)2HPO4] can alter soil pH according to Equation 2. 2 (NH4)2HPO4(s) + H2O(l) 4 NH4+(aq) + HPO42-(aq) + H2PO4-(aq) + OH-(aq)

Only weakly basic, H20 is nearly constant The salt in Equation 2 is the fertilizer (NH4)2HPO4, and the reaction shows that the substance is basic.

Formulas for Power

P = IV P = E/t P = V^2/R P = (I^2)R ------------- P= W(in joules)/ Time (in secs) P= F(in newtons)*v(meters/sec) P= (Force * Displacement)/time

Phosphine (PH3) has which of the following Lewis structures? How did you know?

Phosphorous will bond with three atoms to form a full octet (because it is 3 columns away from nobel gas). It has 5 valence electrons total because it is the 5th column from the right.

Passage Shows Reaction results of mixing various solutions of cations and anions. Results indicate either precipate formed or no reaction. In Table 1, which cation allowed for the greatest number of soluble compounds?

Precipitate formation indicates the solution is fully saturated! Question is asking for the cation that resulted in the greatest number of soluble compounds! According to Table 1, Ag+ had one soluble compound, Ca2+ had three soluble compounds, and Cu2+ and Fe3+ each had two soluble compounds. Ca2+ had the greatest number of soluble compounds. Thus, B is the best answer.

Answer is I

Radioactive tritium (3H) labeled guanine has been used to measure the rate of biochemical processes that involve its binding or incorporation.

Compared to the rate of the reaction between Reactants X and Y at 300 K, the rate of the reaction at 400 K would be:

Rates of chemical reactions always increase with increasing temperature, since a greater number of molecules possess enough energy to overcome the energetic barrier to reaction - the activation energy - at higher temperature.

Why are the percentages of the change in frequency and wavelength much greater when sound waves are used instead of radio waves in these experiments? Practice process of elimination (notice two of the answer choices are saying the same thing)

Remember Radio waves are part of EM spectrum. Sound waves are separate. Light travels faster than sound! The Doppler equation for frequency is Δf/f = -v/c for a given relative velocity v between source and detector. Thus, the frequency shift Δf depends inversely on the speed of the wave in the medium in which it propagates, c. The velocity of sound is much smaller than that of electromagnetic radiation, so for the same relative velocity the frequency and wavelength shifts are much greater for sound than for radio waves.

Relationship between wavelength and speed according to doppler effect?

Remember c=wavelength* frequency The linear relation between relative speed v and change in detected wavelength is a consequence of the Doppler equation, Δλ/λ = v/c where c is the velocity of the radio wave. Furthermore, Graph A is the only one that shows an increase in wavelength Δλ with an increase in speed as the jet flies away from the receiver.

An object that is totally immersed in benzene (specific gravity = 0.7) is subject to a buoyancy force of 5 N. When the same object is totally immersed in an unknown liquid, the buoyancy force is 12 N. What is the approximate specific gravity of the unknown liquid?

SET UP A RATIO! The buoyant force on an immersed object is the product of: (density of the liquid) × (volume of the object) × (acceleration of gravity). Forming the ratio of buoyant forces in the two cases gives: 12/5 = (density of the unknown liquid)/(density of benzene, 0.7). Solving for the specific gravity of the unknown liquid, which is the ratio of its density to that of water, gives (12/5) × 0.7 = 1.7. Answer C is correct.

For most liquids increasing pressure and decreasing temperature converts the liquid to what phase state? What is the exception to this rule

SOLID Except for water which at low temps and increasing pressure will become liquid (because it's liquid state is more dense!)

What is the molar concentration of Na+(aq) in a solution that is prepared by mixing 10 mL of a 0.010 M NaHCO3(aq) solution with 10 mL of a 0.010 M Na2CO3(aq) solution?

Since 1 equivalent of NaHCO3 provides 1 equivalent of Na+, the molar concentration of Na+(aq) in 0.010 M NaHCO3(aq) solution is also 0.010 M = 0.010 mole/L. The molar concentration of Na+(aq) in 0.010 M Na2CO3(aq) solution is 0.020 mol/L since 1 equivalent of Na2CO3 provides 2 equivalents of Na+. When equal volumes of these two solutions are mixed, the resulting molar concentration is equal to their average, (0.010 mol/L + 0.020 mol/L)/2. Thus, B is the correct answer.

What bonding accounts for the expected increase in energy density of solid nitrogen as compared to methanol?

Solid nitrogen contains only covalent bonds. Methanol contains only covalent bonds within each molecule but is capable of intermolecular hydrogen bonding because of the -OH group.

Which extraction procedure will completely separate an amide from the by-product of the reaction between an amine and excess carboxylic acid anhydride?

Solution: The correct answer is A. This is an Organic Chemistry question that falls under the content category "Separation and purification methods." The answer to this question is A because the by-product of the reaction will be an acidic carboxylic acid and the excess unreacted starting material will also be acidic. Extraction with aqueous base will hydrolyze and extract both of these into the aqueous layer, leaving the neutral amide in the ether layer. It is a Reasoning about the Design and Execution of Research question because you are asked to reason about the appropriateness of various procedures in a scientific experiment.

Why did the liposomes fluoresce during size-exclusion chromatography? Liposomes were synthesized from 1 mL of various concentrations of Compound 1 (0.05-0.20 mM) at pH 7 by ultrasonication and agitation in the presence of fluorescent dye that emitted light at 520 nm when excited at 460 nm. An aliquot of the liposomal suspension was subjected to size-exclusion chromatography and results are shown in Figure 1. Further aliquots of the liposomal suspensions of Compound 1 had their pH adjusted from 2-12. Results from size-exclusion chromatography indicated no changes occurred.

Solution: The correct answer is B. This is a Biochemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is B. Liposomes can be difficult to detect since they do not absorb visible light and many molecules absorb UV light. The experimental design allowed fluorescent dye to be trapped inside during liposome formation, which allowed their detection by fluorescence spectroscopy. It is a Reasoning about the Design and Execution of Research question because you are asked to reason about the features of a research study that suggests relationships between the variables.

The overall reaction for glycolysis: Glucose + 2NAD+ + 2ADP + 2Pi → 2Pyruvate + 2NADH + 2H+ + 2ATP + 2H2O can be broken down into two separate processes (reactions 1 and 2). Glucose + 2NAD+ → 2Pyruvate + 2NADH + 2H+ Reaction 1: ΔG° = -146 kJ/mol ADP + Pi → ATP + H2O Reaction 2: ΔG° = +30.5 kJ/mol What is ΔG° for glycolysis?

Solution: The correct answer is C. This is the result if you subtract 2 × ΔG° for Reaction 2 instead of adding it. This is the result if you subtract ΔG° for Reaction 2 from ΔG° for Reaction 1. Glycolysis is the net sum of Reaction 1 and two rounds of Reaction 2. The overall free energy change can therefore be calculated as (-146 kJ/mol) + 2(30.5 kJ/mol) = -85 kJ/mol. This is the result if you add 3 × ΔG° for Reaction 2 to ΔG° for Reaction 1.

why is coefficient of kinetic friction less than static coefficient?

Static friction have greater value than the kinetic friction because static friction acts when the body is at rest. and there is much more inter molecular attraction between the object and the surface for a long time which is required to be overcome first.

During distillation, superheating of the reaction mixture should be avoided. Which of the following would prevent superheating?

Surface tension can cause superheating because it can inhibit the formation of bubbles. Boiling chips are made of nonreactive porous material and provide nucleation sites where small bubbles of vapor can form. This effect overcomes the surface tension and allows the liquid to boil evenly at its normal boiling temperature, thereby preventing superheating.

A small negatively charged particle is placed near a fixed positively charged particle (Q). Which of the following describes the motion of the negatively charged particle?

The answer is it accelerates because Electric Force changes as the distance between the charge and stationairy charge changes. Also remember if there is a net force there is always a net acceleration! Fnet=ma

Question Which of the following is a second period element that is a covalent network solid in its standard state? A. Carbon B. Phosphorous C. Oxygen D. Iodine

The answer to this question is A because Carbon is a second period element that is a covalent network solid (graphite) in its standard state.

The limiting reagent in the experiments described in the passage is: A. iodine. B. zinc. C. methanol. D. iodide. Iodine and zinc are the reactants in an experiment to find the stoichiometry of a reaction. Gray, granular zinc metal (2.0 g) and purple iodine crystals (2.0 g) are added to an Erlenmeyer flask containing 25 mL of methanol (CH3OH). What does this mean? A 2:1 ratio of moles of iodine atoms to zinc atoms in the product is consistently obtained. The mass of iodine and reacted zinc equals the mass of product.

The answer to this question is A because the number of iodine atoms provided in the reaction is less than the 2:1 ratio with zinc atoms that is required for a stoichiometric reaction. This is just saying that the consumption of reactants is equal to what was generated in the products.

What does structure of heme look like?

The answer to this question is A, because the cofactor is heme, which is a porphyrin. The basic unit of a porphyrin is the pyrrole ring, a five-sided heterocycle containing one nitrogen atom.

When two amino acids are joined via a peptide bond, what is the mass of the byproduct of this reaction? (Note: Assume that the amino acids were not modified by protecting groups.)

The answer to this question is B because the formation of a peptide bond is accompanied by the formation of water as a by-product, and the mass of water is 18 amu.

What was the most likely purpose of adding bovine serum albumin to the kinetics experiments in the passage? Bovine serum albumin: The experiment was initiated by adding 50 µL of protein solution (150 µg/mL), which included 0.1 mg/mL bovine serum albumin (BSA). BSA constitutes up to 50% of the mass of protein found in blood serum and mobilizes proteins and lipids.

The answer to this question is B since the passage specifically states that albumin is a protein that mobilizes proteins and lipids in serum. In the context of a kinetics experiment it is perfectly logical to assume that albumin is added to maintain homogeneity and prevent the enzyme from adhering to walls and other surfaces which would inhibit its activity.

Given that the speed of sound in the rat tissues was 1500 m/s, the wavelength of the ultrasound wave used in the study was closest to:

The answer to this question is D because the wavelength is given by (1500 m/s)/(2.3 MHz) = 0.65 mm.

At a given temperature, the resistance of a wire to direct current depends only on the:

The correct answer is B. The resistivity relation at a fixed temperature is Thus, B is the best answer.

If oligonucleotides such as mRNA were not degraded rapidly by intracellular agents, which of the following processes would be most affected?

The destruction of mRNA prevents continuous protein production, allowing the cell to change its protein expression over time. B is the best answer because the coordination of cell differentiation during development is extremely sensitive to the timing of mRNA turnover.

A pump is used to force an aqueous solution through a pipe at high temperature according to Poiseuille's Law: where ΔP is the pressure difference applied by the pump, r is the radius of the pipe, L is the length of the pipe, and η is the viscosity of the solution. Which graph depicts the rate of energy consumed over time in order to maintain constant flow through a pipe subject to boiler scale? NOTES Passage says.... Second, hard water produces boiler scale, a layer of insoluble carbonates formed by Reaction 2 that lines the inner walls of pipes and hot-water boilers, so that the pipes' radii constantly decrease in time. Deposits of this type are especially bad in hot water and are poor conductors of heat.

The energy consumed by the pump is used to create the pressure difference that maintains the viscous flow through the pipe. For a constant flow to occur while the pipe's diameter decreases, the pressure difference should increase in time. According to Poisseuille's Law, at constant flow rate, the pressure difference is inversely proportional to the radius of the pipe to the fourth power. The energy used is equal to the work done in moving the fluid, hence is proportional to the pressure difference. In other words, energy is inversely proportional to the radius of the pipe to the fourth power. As the radius decreases in time, the energy used increases more due to the fourth power dependence of the radius. In other words, more power (energy per unit time) is required to maintain the same flow through a pipe with decreased radius. Hence, the only choice that depicts such a power increase that is getting larger in time is shown in graph D.

What is the electronic configuration of the Co(II) center found in vitamin B12?

The energy of an orbital depends upon the sum of values of the principal quantum number (n) and the azimuthal quantum number (l). This is called (n + l) rule . According to this rule, " In neutral isolated atom, the lower the value of (n+ l) for an orbital, lower is its energy. This is a General Chemistry question that falls under the content category "Atoms, nuclear decay, electronic structure, and atomic chemical behavior." The answer to this question is A. Co(II) is a dication and is formed from the atomic element by the loss of two 4s electrons. As a consequence, only seven 3d electrons remain in the valence shell. It is a Scientific Reasoning and Problem Solving question because you are asked to bring together theory and evidence to draw a conclusion

A way to make lower-toned instruments would be to use: The fundamental frequency f of a string is given by its length L, tension T, and mass per unit length ρ as f= (T/ρ)1/2/(2L).

The equation in the passage also gives the relation between frequency and string density f α (1/r)1/2. Therefore, to lower the frequency one would increase the string density. Choice C is the best answer.

The glass that is used as a beam splitter is replaced with glass that is identical except that it has a 10% higher index of refraction. Which of the following changes will occur to the pinhole image?

The examinee is asked what an increase in the index of refraction of the beam splitter will do to the image of a pinhole on the viewing screen. The pinhole image is formed by light that: (1) passes through the glass of the beam splitter, (2) reflects off the retroflector, (3) returns to the surface of beam splitter nearest the retroflector, (4) reflects off that beam splitter surface, and (5) falls on the viewing screen, forming an image. The only refraction occurs in step (1), when the entering light is refracted. This refraction shifts the rays of light over a bit. If the index of refraction is increased, this increases the shift. This will cause a shift in the position of the light striking the retroflector which will persist through the steps (3), (4), and (5) above, causing the image on the screen to shift in position.

Which of the following expressions is equal to a, the acceleration vector of the box as it moves from Point B to Point C? (Note: The coefficient of friction between the box and the surface between Point B and Point C is equal to μkh) A

The examinee must determine the acceleration of the mass as it slides from B to C across a horizontal surface. As the mass slides across the horizontal surface it will slow due to a leftward kinetic friction slowing the mass, as friction opposes the motion. The kinetic friction is given by -μkhNi, where N denotes the normal force of the surface on the bottom of the mass. For a free mass on a flat surface, the upward normal force cancels the downward gravity force, mg, hence N = mg which yields a friction force -μkhmgi. This is the net force that acts equals ma, according to Newton's Second Law, thus ma = -μkhmgi or a = -μkhgi. Thus, D is the best answer.

Ball 2 is in the water 20 cm above Ball 3. What is the approximate difference in pressure between the 2 balls?

The examinee must determine the pressure difference between two locations in water at depths separated by 20 cm. The absolute pressure p at depth h below the surface of a fluid is: p = p0 + ρgh, where p0 is the atmospheric pressure above the liquid, ρ, is the density of the liquid, and g = 9.8 m/s2. Thus, the pressure difference Δp between two locations in the water would be Δp = ρgΔh, where Δh is the difference in depth. Here, Δh = 20 cm = 0.20 m. Thus, Δp = (1000 kg/m3)(9.8 m/s2)(0.20 m) = 1960 Pa = 2.0 x 103 Pa. Thus, C is the best answer.

An astronaut on Earth notes that in her soft drink an ice cube floats with 9/10 of its volume submerged. If she were instead in a lunar module parked on the Moon where the gravitation force is 1/6 that of Earth, the ice in the same soft drink would float:

The floating ice cube implies that its weight is balanced by the buoyant force on it mg =pVg g cancels out when you solve for V Note that both the weight and the buoyant force are proportional to g, making the numerical value of g irrelevant to the volume of the ice cube that is submerged. Thus, B is the best answer.

As the speed of the jet flying away from the receiver increases, what happens to the distance between adjacent peaks of the transmitted waves, as measured at the receiver? Why?

The increase in distance between radio wave peaks due to the jet speed causes the received wavelength to be lengthened. This effect is the essence of the Doppler effect. As speed increases wavelength increases

What is the approximate number of wavelengths of light that can travel in 1 direction within a retroreflecting bead that has a diameter of 5 × 10-5 m? (Note: The speed of light = 3 × 108 m/s, and its frequency is approximately 1015Hz.) A

The item gives the speed of light to be v = 3.0 × 108 m/s and the frequency to be f = 1015 Hz. The wavelength λ of the light may be found from the relationship for wave speed v = λf, thus, λ= v/f = (3.0 × 108 m/s)/( 1015 Hz) = 3.0 × 10-7 m. The number of waves that will fit along a diameter is found by dividing this wavelength into the diameter D = 5.0 × 10-5 m, so the number of waves is D/λ =(5.0 × 10-5 m)/( 3.0 × 10-7 m) = 1.7 × 102.

Another explanation for this question What was the experimentally determined value of KNAG from the study described in the passage?

The key to realizing this is that MCAT will always ask simple things in the most complex ways. Once you go back to the passage and see they provide an equation and a line graph, you should be thinking ok maybe this relates to michealis menten or y=mx + b It is not quite Michaelis menten because it is not in the format of V= (Vmax)(S) / (km) + (s) ' Now all you are left with is y=mx + b, then you can see the graph, the y= Knag/ Kapp and the x is [NAG] -- thus leaving "1" to be the y-intercept and Knag to be the slope. You can then plug and chug like people suggested. I personally did an estimate of the slope because if you look at the highest value its coordinate is (0.02, 2.0) and the first value is (0, 1.0) ** you always want to pick the simplest numbers** So your rise is 1 and your run is 0.02.

A 7-N force and an 11-N force act on an object at the same time. Which of the following CANNOT be the magnitude of the sum of these forces?

The largest net force occurs when the forces point in the same direction; then, the magnitudes will add mathematically to a value of 18 N. Similarly, the smallest net force occurs when the forces point in opposite directions and the lesser magnitude is subtracted from the greater; this results in a value of 4 N. Of the answers listed, only A (2 N) does not fall between these values. Thus, A is the best answer. Pick the highest possible value and the lowest possible value 4-18 (note magnitude is absolute value!)

Which of the following statements best explains why the intensity of sound heard is less when a wall is placed between a source of sound and the listener?

The listener hears less sound but the same frequency and wavelength as unimpeded sound (decibels corresponds to energy/intensity Sound wave are reflected and absorbed when incident on materials just as light waves are. In doing so the waves are reduced in their forward intensity (units of J/m2). When a wall is placed between a source of sound and the listener, some of the sound energy is transmitted to the listener, but some is reflected and sent backward toward the source or absorbed in the material. The listener hears less sound, but at the same frequency and wavelength as the unimpeded sound.

Which of the following best describes the energy conversion that is taking place when the toboggan is sliding from Point A to Point B? READ QUESTION OPTIONS CAREFULLY

The main energy conversion of the objects sliding from Point A at the top of the hill to Point B at the bottom of the hill is: potential energy to kinetic energy. However, because a frictional force acts on the toboggan, part of the potential energy is converted to heat (thermal energy). Choice C is the best answer.

stereocenters in triglyceride

The middle carbon of the glycerol

An electron is ejected from the cathode by a photon with an energy slightly greater than the work function of the cathode. How will the final kinetic energy of the electron upon reaching the anode compare to its initial potential energy immediately after it has been ejected?

The near equality of the photon energy and the work function means that little initial kinetic energy will be left for the electron. This initial kinetic energy is small compared to the 50 eV it will gain from the potential difference between electrodes. Basically when electron is ejected it has no KE and just PE because it is an Electric Field this gets converted to KE (which is highest right before it reaches anode)

Which of the following nucleotide sequences describes an antisense molecule that can hybridize with the mRNA sequence 5′-CGAUAC-3′?

The only correct sequence is C, which is 3′-GCUAUG-5′. The question asks the examinee to identify the sequence of an antisense molecule that could hybridize with the mRNA sequence 5′-CGAUAC-3′. When the RNA molecules hybridize, the antisense molecule would line up in an antiparallel fashion with the sense molecule, meaning its 3′ end would line up with the 5′ end of its complement. The nitrogenous bases would form the following pairs: A with U, G with C. The

The phase difference corresponding to a half a wave (aka out of phase)

The phase difference corresponding to a half of a wave is 180°. Half a wave difference in phase between two waves corresponds to destructive interference.

The table above gives pressure measured at various depths below the surface of a liquid in a container. A second liquid, whose density is twice that of the first liquid, is poured into a second container. Similar pressure measurements are taken for the second liquid at various depths below the surface of the second liquid. What is the pressure at a depth of 10 cm for the second liquid?

The pressure in a liquid due to the gravitational force of the liquid above a given depth is proportional to the density and the depth. Although the pressures shown in the table change linearly with depth (an increase of 200 N/m2 per 5 cm of depth), the data also imply an extra pressure of 50 N/m2 at zero depth. For the same depth, the liquid with twice the density will create twice as much pressure as the first liquid, but the zero-depth pressure must be added to get the total pressure (2 × 400 +50) N/m2.

In a radioactive series, a nucleus decays through several steps. The thorium series starts with a atom, then emits 1 alpha, 2 beta, 4 alpha, 1 beta, 1 alpha, and 1 beta, in succession. The final product of the series is:

The question lists six alpha decays overall. One alpha decay decreases the atomic mass by 4 and decreases the electric charge by 2, so the effect of six alpha decays would yield an unknown nucleus X via the reaction , thus the result is . The question also lists four beta decays. One beta decay makes no change to the atomic mass, but it increases the electric charge by 1, so the four beta decays will, overall, not alter the atomic mass but the electric charge will be increase by 4 × (+1) = +4 which may be represented by yielding for the final unknown nucleus .

See back answer Since pH = -log[H+], an increase in [H+] results in a decrease in pH. An acid-base reaction does occur. Moreover this reaction will affect the pH of the solution since weak bases are eliminated from solution. Removal of weak bases such as RCO2- results in a decrease in pH, and a decrease in [OH - ]. The effect on pH is always the same for the three cations listed.

The scientists who developed the experimental protocol described in the passage chose TNBS over many potential candidates to label PE molecules. What characteristic about the rate of reaction between TNBS and outer envelope PE molecules allowed the experiment to provide useful data? The rate of TNBS reaction with outer envelope PE molecules is: A. ph increase as H+ increase B.No change in pH C. PH decreases as OH- decrease D. Effect on pH depends on identity of M2+ metal

If Reactants X and Y are atoms, what is the shape of the product molecules? Y2X

The shape of a molecule depends on the number of valence electrons at the central atom since lone pairs of electrons exert stereochemical effects. Without the group numbers of the reactant atoms, it is impossible to determine the molecular shape of the product. If X = C, and Y = O, then the molecular geometry would be linear. If X = O and Y = H, however, the molecular geometry would be bent.

The sled and rider start from a location on the hill that is 10 m lower than Point A. How does the speed of the sled and rider at Point B, starting from this location, compare to the speed of the sled and rider at Point B when starting from the top of the hill?

The sled and rider are free of friction sliding down the hill. Equating the loss of potential energy (mgh) to the gain of kinetic energy (mv2/2), the ratio of speeds at the bottom of the hill when starting at h = 10 m and at h = 20 m is: v210/v220 = 10/20. Taking the square root gives: v10/v20 = (1/2)1/2 or v10 is slower than v20 by a factor of 21/2. The correct answer is D.

In the macronucleus, the genes for rRNA are located extrachromosomally. This suggests that the rRNA genes are:

The stem of this item states that the rRNA genes are extrachromosomal and asks what this suggests. Genes are strands of DNA, so this must mean that they are strands of DNA that are not part of the cell's chromosomes. These strands still must self-replicate just as the chromosomes do if they are to be passed from one generation to the next, so choice C is the correct answer. All nucleic acids are a linear arrangement of the component nucleotides, so choice A is incorrect. The rRNA genes must be functional or the organism could not produce protein, so choice B is incorrect. Finally, the fact that they are extrachromosomal gives no clue to their arrangement, so choice D can also be rejected.

A nucleus splits into two fragments that have equal charge but unequal mass. Which of the following is equal for the two fragments as they move apart?

The unequal-mass fragments move apart under the influence of the mutual Coulomb forces. These forces are equal and opposite (Newton's third law). Other answers are incorrect because of the differing fragment masses. Thus, answer A is the correct choice.

A gas laser has a cavity length of 1/3 m and a single oscillation frequency of 9.0 x 1014 Hz. What is the cavity mode number?

The wavelength is given by the speed (3 x 10 8 m/s) divided by the frequency (9.0 x 1014 Hz), which givesλm = 0.33 x 10-6m. Using the equation given in the passage, m = 2L/λm, gives the cavity-mode number, m = 2 x 106. Answer B is correct.

What is the volume flow rate of blood that moves at 0.20 m/s through an artery with a diameter of 1.0 × 10-2 m?

This is Flow rate Q=Av This question is asking for VFR Volume flow rate is the product of blood speed and artery cross-sectional area: (0.20 m/s)·(π/4)·(1.0 × 10-2 m)2 = 5π × 10-6 m3/s. Therefore, answer choice B is the best answer.

What formula are you likely going to need? Assume the hydrolysis of ATP proceeds with ΔG′° = -30 kJ/mol. ATP + H2O → ADP + Pi Which expression gives the ratio of ADP to ATP at equilibrium, if the [Pi] = 1.0 M? (Note: Use RT = 2.5 kJ/mol.)

This is a General Chemistry question that falls under the content category "Principles of chemical thermodynamics and kinetics." The answer to this question is D. The free energy of the reaction ΔG′° is related to the equilibrium constant Keq = [ADP][Pi]/[ATP] as ΔG′° = -RTln(Keq). Applying [Pi] = 1 and using the expression for Keq gives ΔG′° = -RTln([ADP]/[ATP]), so that [ADP]/[ATP] = e(30/2.5) = e12. It is a Scientific Reasoning and Problem Solving question because you are asked to determine and use a scientific formula to solve a problem.

If [E]T was the concentration of lactase in the kinetics trials, what expression gives the concentration of lactase in the commercial preparation of this enzyme? The students prepared stock solutions of Compound 1 in four different concentrations in pH 7 buffer. A stock solution of the enzyme was prepared by diluting 0.100 mL of the commercial preparation to 25.0 mL in the buffer solution. Experiments were initiated by mixing 1.0 mL of each substrate solution with 1.0 mL of the enzyme solution.

This is a General Chemistry question that falls under the content category "Unique nature of water and its solutions." The answer to this question is D because the commercial preparation was first diluted by 1 → 250 to prepare the stock solution, and it was further diluted by 1 → 2 by mixing with the substrate stock solution to perform the kinetics experiments. It is a Scientific Reasoning and Problem Solving question because you are asked to bring together theory, evidence, and observations to draw a conclusion.

Which experimental feature of the MALDI-MS technique allows the separation of ions formed after the adduction of tissue molecules? Matrix-Assisted-Laser-Desorption/Ionization (MALDI) is a soft ionization technique used in conjunction with mass spectrometry (MS) to analyze proteins, protein fragments, and peptides. In MALDI, a plate containing the sample is coated with 2,5-dihydroxybenzoic acid (DHB) (structure shown).

This is a Physics question that falls under the content category "Translational motion, forces, work, energy and equilibrium in living systems." The answer to this question is B because the passage states that all ions travel the same distance of 0.5 m to the MS detector within the uniform electric field E region, and that the velocity of the ions is inversely proportional to their mass-to-charge ratio (m/z). Thus, the fastest ions are those with smallest m/z ratio, and these ions arrive first at the MS detector, being separated from the slower ones. It is a Reasoning about the Design and Execution of Research question because you must reason about the features of research work that indicate association between variables.

For what mechanistic reason does G1 of lactase first act as a Brønsted acid during catalysis? A glutamate residue (Glu-1) in the active site donates a proton to an oxygen atom. Another glutamate on the opposite axial side (Glu-2) acts as a nucleophile to liberate D-glucose and generate an α-D-galactopyranosyl-modified enzyme intermediate. Then, Glu-1 deprotonates water, and the resulting hydroxide ion acts as a nucleophile to liberate β-D-galactose and regenerate the enzyme.

This is an Organic Chemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is C. Protonation of the oxygen atom in glucose makes this substance a better leaving group in much the same way that protonation of an alcohol facilitates substitution of an -OH group. It is a Scientific Reasoning and Problem Solving question because you are asked to bring together theory, evidence, and observations to draw a conclusion.

When the wavelength for maximum light emission of a given scintillator is 450 nm, what is the energy of the light photon?

To find the energy E of a photon from its wavelength λ , use the formula: E = hc/λ . The constants h and c are given in the passage. Therefore E = (6.6 x 10-34 J∙s) x (3 x 108 m/s)/(450 x 10-9 m) = 4.4 x 10-19 J. Answer A is correct.

What are the two requirements of an electrolytic cell compared to a galvanic cell?

Two requirements of an electrolytic cell are that a redox reaction occur and that the potential be negative. Galavanic reaction has a positive reduction potential (spontaneous)

For a given laser-cavity mode, the standing-wave pattern within a laser cavity can be viewed as a superposition of two traveling waves. Their amplitudes and directions are described by which of the following?

Two traveling waves that make up a standing wave of the type shown in the passage must have equal amplitudes and move in opposite directions. Otherwise, the wave superposition does not produce a stationary-wave envelope. Answer A is correct.

Which experimental approach can be used to analyze the metal content of soapy precipitate produced by Reaction 1? Dissolve the solid in a known volume of: WHAT IS THIS QUESTION REALLY ASKING

What is the soapy precipates? It is the salt of a weak base!

Take the inverse!!! This is a Biochemistry question that falls under the content category "Principles of chemical thermodynamics and kinetics." The answer to this question is B because KM is the concentration of substrate at which the kinetics experiment reaches half the maximum velocity and this can be read from the graph shown in Figure 1. It is a Data-based and Statistical Reasoning question because you are asked to analyze and interpret the graphical information presented in Figure 1 to arrive at the conclusion.

What is the value of KM (in µM) for the WT enzyme?

The scientists who developed the experimental protocol described in the passage chose TNBS over many potential candidates to label PE molecules. What characteristic about the rate of reaction between TNBS and outer envelope PE molecules allowed the experiment to provide useful data? The rate of TNBS reaction with outer envelope PE molecules is: wHAT IS THIS QUESTION REALLY ASKING?

What is this experiment trying to answer/test? End goal of the reaction is to "freeze" membrane so next we need ask what will ensure this?

WORK ON YOUR MATH Make sure you are using the experimental volume not the eletuant volume if all else fails just make sure exponents are right

What mass of Compound 1 (MW = 800 g/mol) is contained in the solution used to prepare liposomes that elute at 20 mL by size-exclusion chromatography? Liposomes were synthesized from 1 mL of various concentrations of Compound 1 (0.05-0.20 mM) at pH 7 by ultrasonication and agitation in the presence of fluorescent dye that emitted light at 520 nm when excited at 460 nm. An aliquot of the liposomal suspension was subjected to size-exclusion chromatography and results are shown in Figure 1. Further aliquots of the liposomal suspensions of Compound 1 had their pH adjusted from 2-12. Results from size-exclusion chromatography indicated no changes occurred.

This is a General Chemistry question that falls under the content category "Unique nature of water and its solutions." The answer to this question is B because the graphs in Figure 1 both imply a 1:1 mole ratio of NAG3 was added at the equivalence point and the solution contained 1.0 mL of 0.10 mM = (1 × 10-3 L)(0.10 × 10-3 mol/L) = 1.0 × 10-7 mol = 100 nmol.

What quantity of NAG3 was required to reach the equivalence point in the titration?

This is a Biochemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is D since, according to Equation 1, the slope of the graph in Figure 2 is the value of KNAG. The slope is Δy/Δx = (2 - 1)/(0.020 - 0.00) = 1/0.020 = 50. It is a Data-based and Statistical Reasoning question because you are asked to analyze and interpret the graph presented in Figure 2 to arrive at the conclusion.

What was the experimentally determined value of KNAG from the study described in the passage?

What happens to angle of refraction? Light Travels Low n (high speed) to High N (low speed)--> Light travels from High n (low speed in material) to Low n (high speed in material)

When light crosses an interface into a medium with a higher index of refraction, the light bends towards the normal. Conversely, light traveling across an interface from higher n to lower n will bend away from the normal (angle will be higher than angle of incidence)

Correct answer This is a Physics question that falls under the content category "Translational motion, forces, work, energy and equilibrium in living systems." The answer to this question is D because the wavelength must be either 266 nm or 325 nm, and by doubling the frequency of the laser whose wavelength is 532 nm, the resulting wavelength is 532 nm/2 = 266 nm, because electromagnetic radiation wavelength and frequency are inversely proportional to each other. Also, the power of the radiation must be 1.5 mW. It is a Reasoning about the Design and Execution of Research question because you must reason about the appropriateness of tools used to conduct natural sciences research, such as lasers.

Which laser is suitable for the MALDI technique after its frequency is doubled?

Correct answer issss A

Which of the following compounds is most likely to be a major product in Step 2 if the aldol condensation is NOT followed by a dehydration reaction?

The answer to this question is B because the pK is the pH at which the fraction of folded DNA is 0.5. This occurs at the lowest value in 5hmC-WT. Cooperativity is measured as the slope of the unfolding transition. This is also highest in 5hmC-WT.

Which statement about the unfolding cooperativity and pK of the oligonucleotides is consistent with the data in Figure 1? A. The oligonucleotide with the highest pK displays the highest unfolding cooperativity. B. The oligonucleotide with the lowest pK displays the highest unfolding cooperativity. C. The oligonucleotide with the second highest pK displays the highest unfolding cooperativity. D. The oligonucleotide with the second highest pK displays the lowest unfolding cooperativity.

Correct answer A The answer to this question is A, because the cofactor is heme, which is a porphyrin. The basic unit of a porphyrin is the pyrrole ring, a five-sided heterocycle containing one nitrogen atom.

Which structure represents a component of the HRP cofactor?

Sound of a known frequency, wavelength, intensity, and speed travels through air and bounces off an imperfect reflector which is moving toward the source. Which of the following properties of the sound remains the same before and after reflection?

Within still air, the speed of sound remains constant. Thus, A is the best answer.

What is true for this scenario: If I throw a ball in the air and catch it. What is the relationship between initial and final velocity. Assumption: No air resistance and the only force acting on the ball is gravity.

Yes. But only in magnitude. The direction will obviously be opposite. When you throw the ball up, it has some total energy = kinetic + potential. The kinetic energy is due to the initial velocity you provide, and the potential is due to gravity, 𝑈=𝑚𝑔ℎ is the initial height the ball is thrown from. conservation of energy tells you that the total energy has to be constant. The only way this can happen is if the kinetic energy is also same at the initial point. That is, it has the same speed.

When you are mixing two solutions what do you need to do to find the final concentration of one particular ion?

You must average their molar concentrations!

When a weak acid is titrated with a strong base the resulting equivalence point will occur at what pH?

a slightly basic pH The pH at the equivalence point in any titration is the pH of the salt solution formed. At the equivalence point of the titration, the solution contains sodium benzoate and water. The passage states that benzoic acid is a weak acid; therefore, its conjugate base, the benzoate anion, is a stronger base than H20 and reacts with water to produce OH- and undissociated benzoic acid (HA). The resulting solution then has a pH > 7, because of the hydroxide ions produced by this reaction. The reaction of an ion such as benzoate ion with water is called hydrolysis.

STP (standard temperature and pressure)

is used for the ideal gas law, and it is 273K, 1 atm of pressure. Memorize that 1 mole of ideal gas at STP occupies 22.4 L.

Which of the following best describes the movement of an electron after it is ejected from the cathode? (Released into an electric field)

it accelerates! This is always true wherever there is a Force (m*a) and velocity is not constant! A charged particle accelerates in an electric field. The electron starts with a velocity that increases as it approaches the anode through the vacuum.

What do you assume if an object is floating?

mg=Fb=pVg

What is the approximate molarity of the solution prepared by the instructor? Given 8g of NaOH (MM=40g) in 2 L of water

moles= 8/40= 1/5 moles=> .20/2liters = .1M I hope you are embarrassed you got this wrong! The instructor dissolved (8 g)/(40 g/mol) = 0.2 mol NaOH in 2 L of H2O, or 0.1 mol in 1 L of H2O.

Formula for number of possible petides that cotain one each of n amino acids nx2x1 The general formula to calculate number of peptide bonds is n — 1, where n is number of amino acids present in peptide or protein.

n!= 3! so 3x 2x1

If more reactant is added to a system, the system responds

to counteract that change by using it up, thus producing more product. If a catalyst is used in such a reaction, it will only change the rate of attaining the equilibrium ratio of products and reactants; it will not change the equilibrium ratio.