General Science Praxis Practice Study

Students are given the preceding diagram representing three samples of an ideal gas in rigid containers. The pressure is the same in each container, and the small spheres represent the relative number of moles of molecules in the container. Which of the following student comparisons of the temperatures T in the containers is correct? Answer the question by selecting the correct response. T2>T3>T1 T2>T1>T3 T3>T1>T2 T3>T2>T1

Option (A) is correct. According to the ideal gas law, T equals, the fraction P V over n R, end fractionT=PV/nR , where T is the temperature, P is the pressure, V is the volume of gas, n is the number of moles of molecules of gas, and R is the ideal gas constant. Since P and R are constants, the relative temperatures can be compared using the ratio of V over nV/n; therefore, the correct order is T2>T3>T1

Where in the ocean basins would the youngest rock of the ocean floor be found? Answer the question by selecting the correct response. Trenches found in the deep ocean Abyssal plains Mid-ocean ridges Continental shelves

Option (C) is correct. Mid-ocean ridges are features associated with divergent plate boundaries, where two plates are separating and moving away from each other. At these types of boundaries, magma from the asthenosphere rises up and forces the two plates apart. When the magma reaches the surface, whether on land or on the ocean floor, it cools and hardens to form new crustal rock. Older rocks are found farther away from the mid-ocean ridge as the new magma rises and the two plates continue diverging.

Which of the following statements could a teacher use to help explain the cause of seasons on Earth? Answer the question by selecting the correct response. As Earth orbits the Sun, its tilted axis always points in the same direction, resulting in different parts of Earth receiving the Sun's direct rays. As Earth orbits the Sun, it is at varying distances from the Sun and receives more or less heat from the Sun. As Earth rotates on its axis, different parts of Earth receive sunlight. As the Sun undergoes cyclical changes in solar output, seasonal temperature changes on Earth result.

Option (A) is correct. The north end of Earth's rotational axis points approximately toward the pole star, Polaris, throughout the Earth's orbit. The seasons are caused by the changes in the direction of tilt with respect to the Sun. For example, in the summer, when the north end of the axis is tilted toward the Sun, the Northern Hemisphere receives more direct sunlight for a longer period of time.

If a wire carries a steady current of 0.1 ampere for 20 seconds, which of the following is the total charge passing through the wire during this time interval? Answer the question by selecting the correct response. 0.005 coulomb 2 coulombs 20 coulombs 200 coulombs

Option (B) is correct. Electric current is defined as the charge per unit time passing a given point. A current of 1 ampere is equal to 1 coulomb per second. Thus a steady current of 0.1 ampere in 20 seconds corresponds to a total charge of 2 coulombs.

Of the following types of biological molecules, which contain the most energy per gram? Answer the question by selecting the correct response. Nucleic acids Lipids Carbohydrates Proteins

Option (B) is correct. Lipids have more energy content per gram than nucleic acids, carbohydrates, and proteins. As lipids are metabolized, they undergo exothermic chemical reactions in which energy is required to break bonds in the lipids, but a larger amount of energy is released as new bonds are formed in the products.

Nanotechnology is best described as applications of Answer the question by selecting the correct response. genetically modified bacteria and yeast synthetic materials or devices at the atomic or molecular scale radioactive decay processes data-mining techniques to large data sets

Option (B) is correct. Nanotechnology is the application of synthetic materials or devices at the atomic or molecular scale. Anti-glare and scratch-resistant ultrathin films on sunglasses and stain-resistant and wrinkle-resistant finishes on fabrics are examples of nanotechnology used for consumer products.

Some small organisms do not have lungs, gills, or circulatory systems because Answer the question by selecting the correct response. there is not enough room for these structures in their bodies they do not need to exchange gases with the environment they have enough surface area to accomplish gas exchange directly between their cells and the environment they are ancient species that have not yet evolved circulatory systems

Option (C) is correct. Smaller organisms typically have a larger surface-area-to-volume ratio, allowing gas exchange with the environment to occur at a rate that does not require specialized organs for this purpose.

A tractor is pulling a wagon full of hay. The mass of the wagon and hay is two times the mass of the tractor. When the tractor accelerates forward, the force that the wagon exerts on the tractor is Answer the question by selecting the correct response. two times greater in magnitude than the force that the tractor exerts on the wagon equal in magnitude to the force that the tractor exerts on the wagon one-half the magnitude of the force that the tractor exerts on the wagon zero, since the tractor is pulling the wagon forward

Option (B) is correct. Newton's third law states that for every action, there is a reaction force that is equal in magnitude but opposite in direction to the action force. Thus, the force that the wagon exerts on the tractor must be equal in magnitude to the force that the tractor exerts on the wagon.

Which of the following sets of tools would be most useful in providing conclusive evidence that a chunk of an unknown mineral is calcite? Answer the question by selecting the correct response. A black unglazed porcelain plate and a table of mineral streak colors Dilute hydrochloric acid, an eyedropper, and a hand lens A copper penny, a glass plate, a steel nail, and a Mohs' hardness scale A spring scale, a thin wire, a graduated cylinder, and water

Option (B) is correct. One of the properties that distinguishes the mineral calcite from other minerals is its reactivity with acid. When a drop of dilute hydrochloric acid is placed on calcite, the mineral will fizz, or effervesce, indicating carbon dioxide is released during the chemical reaction. Other carbonates react with acid but more weakly than calcite, and warming the acid or powdering the sample is typically required to observe a vigorous reaction.

Which of the following astronomical objects mainly consists of matter in the plasma state? Answer the question by selecting the correct response. A comet The Sun Jupiter Mercury

Option (B) is correct. Plasma is a superheated state of matter that is a mixture of ionized gases and free electrons. The Sun and other stars are composed of plasma. Plasma is the most common state of matter in the universe.

Which of the following is present in a eukaryotic cell, but not present in a prokaryotic cell? Answer the question by selecting the correct response. DNA Mitochondria Cytoplasm Respiratory enzymes

Option (B) is correct. Prokaryotes lack membrane-bound organelles, such as mitochondria.

Of the following aqueous solutions, which has the highest concentration of NaOH? (The molar mass of NaOH is 40g.) Answer the question by selecting the correct response. 1% NaOH by mass 1 M NaOH 20g NaOH in 1 L of aqueous solution 20 g of NaOH in 1kg of water

Option (B) is correct. The 1M solution is prepared by dissolving one mole, or 40g , of NaOH into enough water to make 1L of solution; therefore, the 1M solution has the highest concentration of the solutions described in the options.

...C6H12O6+...O2→...CO2+...H2O If the preceding chemical equation for the combustion of glucose is balanced using the smallest whole-number coefficients possible, what is the coefficient for O2? Answer the question by selecting the correct response. 3 6 9 12

Option (B) is correct. The balanced equation is C6H12O6+ 6 O2→6 CO2 + 6 H2O

During a chemical process, a system absorbs 4.8 kilojoules4.8kJ of heat while doing 1.2 kilojoules1.2kJ of work on the surroundings. The change in internal energy of the system is Answer the question by selecting the correct response. +4.8kJ +3.6kJ −1.2kJ −6.0kJ

Option (B) is correct. The change in internal energy of the system is equal to the energy absorbed by the system minus the energy used by the system to do work on the surroundings, (4.8kJ−1.2kJ)= 3.6 kJ

The primary reason that stripping the outer and inner bark from the circumference of a tree will eventually kill the tree is that removal of the bark Answer the question by selecting the correct response. makes the tree susceptible to desiccation prevents the transport of sugar to the roots compromises the structural support of the tree prevents the transport of water from the roots

Option (B) is correct. The inner bark contains the phloem, which is living vascular tissue that carries sugar and other organic nutrients from the leaves to other parts of the plant, including the roots. Removing the bark will prevent the flow of sugar to the roots and eventually kill the tree.

If the length of a simple pendulum is doubled, the period of the pendulum will Answer the question by selecting the correct response. increase by a factor of 2 increase by a factor of the square root of √2 remain the same decrease by a factor of 2

Option (B) is correct. The period T of a simple pendulum of length L is given by the equation T equals 2 pi times the square root of the fraction T=2π√L/g , where g is the acceleration due to gravity. If the length of the pendulum is doubled, then the period of the pendulum will increase by a factor of √2

Trout automatically swim or orient themselves in an upstream direction that keeps them from being swept away. This behavior is an example of Answer the question by selecting the correct response. migration kinesis taxis learning

Option (C) is correct. Taxis is a response toward or away from a stimulus. The swimming of trout into a water current is referred to as positive rheotaxis. The behavior points the fish in the direction from which most food appears and keeps the fish from being swept away. The fish detect the current and respond to it through the lateral line system, a mechanosensory system distributed superficially on the skin surface and in fluid-filled canals just under the skin on the head and body of the fish.

The Oort cloud, which is the outermost region of the solar system, consists primarily of which of the following? Answer the question by selecting the correct response. Black holes Star clusters Icy debris Rogue planets

Option (C) is correct. The Oort cloud is the outermost region of the solar system and consists of icy debris possibly dating back to the formation of the solar system. Scientists hypothesize that the Oort cloud is one of the sources of comets in the solar system.

Most of the water on Earth is in the ocean, but fresh water occurs in rivers, lakes, glaciers, and groundwater. Which of the following best helps explain why fresh water exists on Earth? Answer the question by selecting the correct response. Salt water is purified as it flows through the ground. Pure water evaporates from oceans, leaving salts behind, and later precipitates from the atmosphere. Circulation of seawater through the mid-ocean ridges produces fresh water. Salts dissolved in rivers and lakes settle to the bottom with time.

Option (B) is correct. The source of almost all fresh water on Earth is precipitation from the atmosphere, which, in turn, was originally from ocean water that evaporated. When ocean water evaporates, the solids are left behind and only fresh water is transferred to the atmosphere. This allows land-based water, including streams, rivers, lakes, and groundwater, to be considered fresh.

A respiratory control center is located in which of the following structures? Answer the question by selecting the correct response. Heart Pulmonary artery Medulla oblongata Spinal cord

Option (C) is correct. The neurons primarily responsible for regulating breathing are located in the medulla oblongata, near the base of the brain stem. Neural circuits in the respiratory control center detect stretching of the lungs and regulate the degree of lung expansion during inhalation. Neurons in the medulla also use the pH of the blood as an indicator of the necessary depth and rate of breathing. Increased metabolic activity causes an increase in blood CO2 , which dissociates into HCO3− and H+. This causes a decrease in the pH of the blood and of the cerebrospinal fluid that bathes the central nervous system.

Which of the following statements best describes the view of the Moon as seen from Earth during the new moon phase? Answer the question by selecting the correct response. The right half of the Moon appears lit, with the lit part growing larger on successive days. The left half of the Moon appears lit, with the lit part growing smaller on successive days. The lit side of the Moon faces away from Earth, causing the Moon to appear totally dark. The light reflecting off Earth's surface illuminates the entire surface of the Moon.

Option (C) is correct. The new moon phase occurs when Earth, the Moon, and the Sun are approximately aligned, with the Moon passing between Earth and the Sun. Because of this arrangement, observers on Earth cannot see the lit portion of the Moon, which is facing away from Earth, in the direction of the Sun. The new moon lasts for approximately two days during the lunar cycle of phases.

In the root system of a vascular plant, the movement of water from the soil into the plant's root cells occurs by Answer the question by selecting the correct response. capillary action translocation turgor pressure osmosis

Option (D) is correct. Osmosis refers to the passive movement of water into a region of higher solute concentration from a region of lower solute concentration. The concentration of dissolved minerals inside the root hairs is much higher than the concentration outside the root hairs, in the soil; similarly the concentration of water is higher in the soil than in the root hairs, so water enters the large surface area of the root hairs by osmosis.

Of the following organisms, which are primary consumers in an ecosystem? Answer the question by selecting the correct response. Algae Cyanobacteria Frogs Grasshoppers

Option (D) is correct. Primary consumers eat producers, which are autotrophs such as plants, algae, and cyanobacteria. Hence, grasshoppers that eat plants are primary consumers.

Which of the following statements about seismic waves is accurate? Answer the question by selecting the correct response. Seismic waves only travel on Earth's surface. P-waves and S-waves travel at the same speed. Both P-waves and S-waves are transverse waves. P-waves can travel to the opposite side of Earth.

Option (D) is correct. Primary waves, or P-waves, are longitudinal waves and can travel to the opposite side of Earth. The refraction of P-waves as they cross the boundaries between different layers of Earth has provided information about Earth's interior. The difference in the arrival times between P-waves and the slower traveling S-waves can be used to determine the distance from a seismometer to the epicenter of an earthquake.

The height to which a ball bounces is compared to the height from which it is dropped. The ball is dropped from five different heights, and the results are plotted as shown in the preceding graph. On the basis of these data, it should be concluded that the Answer the question by selecting the correct response. height of the bounce is directly proportional to the height of the drop height of the bounce is inversely proportional to the height of the drop data point for the 6-foot drop does not seem to fit the pattern and the drop should be repeated data points for the 8-foot drop and the 10-foot drop do not seem to fit the pattern and the drops should be repeated

Option (C) is correct. Four of the data points fall along a straight line with a positive slope, suggesting that the height of the bounce is directly proportional to the height of the drop. However, the data point for the 6-foot drop is not close to the line, and the drop must be repeated to support or contradict this conclusion.

A teacher shows students the preceding reaction progress diagram in which the enthalpy of the reactants is less than the enthalpy of the products. Of the following student conclusions, which is best based on the diagram? Answer the question by selecting the correct response. Heat is absorbed, and the reaction is exothermic. Heat is produced, and the reaction is exothermic. Heat is absorbed, and the reaction is endothermic. Heat is produced, and the reaction is endothermic.

Option (C) is correct. If the enthalpy of the reactants is less than the enthalpy of the products, then a net absorption of heat occurs during the reaction, and the reaction is described as endothermic. In other words, the total energy required to break the bonds in the reactants is greater than the total energy released when the new bonds in the products form.

A student who is attempting to view red blood cells under a microscope notices that a blue‑colored haze is distorting the image. Which of the following is most likely to eliminate the haze? Answer the question by selecting the correct response. Using a lens with greater magnification Decreasing the amount of light coming through the diaphragm Cleaning the objective lens Bringing the objective lens closer to the slide

Option (C) is correct. If the image is distorted by a haze, it is most likely that the objective lens is dirty from oil and dust particles. The objective lens should be cleaned following the instructions recommended by the manufacturer.

If a beaker and a bathtub are each filled with pure boiling water, which of the following indicates the relative temperatures and heat content of the water in each? Answer the question by selecting the correct response. The temperature is higher in the bathtub, and the heat content is greater in the bathtub. The temperature is higher in the beaker, and the heat content is greater in the beaker. The temperature is the same in both, and the heat content is the same in both. The temperature is the same in both, and the heat content is greater in the bathtub.

Option (D) is correct. Since the water is boiling, the water is at the same temperature in both the beaker and the bathtub. The heat content of a sample of a substance depends on the amount of the substance in the sample and the temperature. Since the bathtub holds more water than the beaker holds and the temperature is the same in both, the sample of boiling water in the bathtub has greater heat content than the sample in the beaker has.

A teacher selects a diagram of the Calvin cycle to use during a lesson on photosynthesis. The teacher selected the diagram most likely to illustrate the steps involved in which of the following processes? Answer the question by selecting the correct response. The oxidation of glucose to form carbon dioxide and water The breakdown of glucose to produce ethanol The conversion of light energy into chemical energy in ATP The fixation of carbon dioxide into sugar molecules

Option (D) is correct. The Calvin cycle fixes CO2 to organic molecules to synthesize the 3-carbon sugar glyceraldehyde 3-phosphate. The products of the light reactions, ATP and NADPH, are used during the Calvin cycle as a source of energy and electrons, respectively.

Which of the following is the ground state electron configuration for Ti? Answer the question by selecting the correct response. 1s^2, 2 s^2, 2 p^2, 3 s^2, 3 p^6, 4 s^2 1s^2, 2 s^2, 2 p^6, 3 s^2, 3 p^6, 4 s^2, 4 p^2 1s^2, 2 s^2, 2 p^6, 3 s^2, 3 p^6, 3 d^4 1s^2, 2 s^2, 2 p^6, 3 s^2, 3 p^6, 4 s^2, 3 d^2

Option (D) is correct. The atomic number for Ti , titanium, is 22; therefore, a neutral atom of Ti has 22 electrons and, using the Aufbau principle, the ground state electron configuration is 1𝑠2 2𝑠2 2𝑝6 3𝑠2 3𝑝6 4𝑠2 3𝑑2.

The elements in the first column in the periodic table have similar chemical properties because they have Answer the question by selecting the correct response. similar densities the same atomic masses the same number of protons in their atoms the same number of outer electrons

Option (D) is correct. The chemical properties of the elements in the first column are largely determined by their electron configurations. Elements in group 1 have one electron in their valence shell and have similar chemical properties.

Bean plants lower their leaves in the evening and raise them to a horizontal position in the morning. The movements will continue even if the plant is kept in constant light or darkness. Such movements are referred to as Answer the question by selecting the correct response. photoperiodism phototropism morphogenesis circadian rhythm

Option (D) is correct. The daily change in the position of the bean plant's leaves dependent on the time of day but independent of light is an example of circadian rhythm. The plants undergo genetically programmed physiological changes that affect the position of the leaves in a cyclic fashion over an approximately 24-hour period.

A teacher preparing a lesson on plate tectonics finds the preceding diagram. The teacher could use this diagram to illustrate which of the following types of fault? Answer the question by selecting the correct response. A normal fault A reverse fault A thrust fault A transform fault

Option (D) is correct. The diagram shows a portion of Earth's crust through which a fault runs. The relative movement along the fault is horizontal, indicating that the fault is a transform, or strike-slip, fault. The San Andreas Fault, which runs through much of California, is a transform fault.

The female parts of a flower are collectively known as the Answer the question by selecting the correct response. ovary stamen petal pistil

Option (D) is correct. The female parts of the flower include the stigma, style, pollen tube, ovary, and ovule and are collectively referred to as the pistil.

If an aqueous solution contains 0.240 mol of H2SO4, how many moles of NaOH are needed to completely neutralize the solution? Answer the question by selecting the correct response. 0.120mol 0.240mol 0.360mol 0.480mol

Option (D) is correct. The neutralization reaction is represented by the chemical equation H2SO4+2NaOH→Na2SO4+2H2O. Based on the coefficients in the equation, twice as many moles of NaOH are needed to neutralize a given number of moles of H2SO4; therefore, 0.480mol of NaOH are needed to neutralize 0.240mol of H2SO4

Which of the following is true of a continental shelf? Answer the question by selecting the correct response. It usually extends a mile or less from the shore. It supports little biodiversity. The water above it is typically more than 10 kilometers deep. It is the undersea extension of a continent.

Option (D) is correct. The term "continental shelf" generally means the part of the continental margin that is between the shoreline and the shelf break, or where there is very little to no noticeable slope. The continental shelf can be virtually absent or it can extend hundreds of miles. Typical water depths along the continental shelf are between 100 and 200 meters. The continental shelf often contains the highest amount of benthic life—that is, the animals and plants that live on the ocean floor.

Most of the mass in Earth's atmosphere is contained in which of the following layers? Answer the question by selecting the correct response. Mesosphere Stratosphere Thermosphere Troposphere

Option (D) is correct. The troposphere is the lowest layer and it contains approximately 80 percent of the atmosphere's mass. The density of Earth's atmosphere gradually decreases with altitude and approaches zero in the upper stratosphere.

Approximately how many atoms of hydrogen are in 1.0 mol of HC2 H3 O2? Answer the question by selecting the correct response. 1.0 4.0 6.0 x 10^23 2.4 x 10^24

Option (D) is correct. There are 4 hydrogen atoms indicated in the formula HC2H3O2, which represents acetic acid. The number of particles in a mole of any substance is given by Avogadro's number, 6.0×10^23; therefore, the number of hydrogen atoms in 1.0mol of HC2H3O2 is 4×(6.0×10^23)= 2.4× 10^24

The west coast of South America is a site that experiences significant coastal upwelling. Which of the following best explains the importance of coastal upwelling? Answer the question by selecting the correct response. It decreases the amount of erosion along the coast. It prevents saltwater intrusion into coastal aquifers. It reduces the intensity of tropical cyclones that hit the coast. It supports high primary productivity and rich coastal fisheries.

Option (D) is correct. Upwelling currents occur when winds blowing across the ocean surface push water away from an area. When this occurs, water rises from beneath the surface to replace the diverging surface water. Subsurface water that rises to the surface as a result of upwelling is typically colder, rich in nutrients, and biologically productive. Therefore, good fishing grounds are found where upwelling is common. The west coast of South America is one such area.

As shown in the preceding figure, a ray of light, L, passes from medium 1 through a boundary into medium 2. What will be the path of the light in medium 2? (n is refractive index.) Answer the question by selecting the correct response. A B C D

Option (D) is correct. When light passes from a medium with a higher index of refraction into a medium with a lower index of refraction, the light will be refracted away from the normal to the interface (the dashed line in the figure), in accordance with Snell's law. Snell's law is represented mathematically by the following equation, where 𝜃1 is the angle of incidence, 𝜃2 is the angle of refraction, v is the speed of light in each medium, and n is the index of refraction for each medium. sinθ2/sinθ1 = v2/v1 = n1/n2

Which of the following best describes how tides are affected when the Sun, Earth, and Moon are in alignment? Answer the question by selecting the correct response. There are no tides, because the gravitational forces due to the Sun and the Moon cancel each other out. The difference between high and low tides does not change over the 28-day lunar cycle. The difference between consecutive high and low tides is relatively small. The difference between consecutive high and low tides is relatively large.

Option (D) is correct. When the Sun, Earth, and the Moon are in alignment (a condition known as syzygy), the tidal force due to the Sun is increased, which reinforces the tidal force produced by the Moon. The difference between consecutive high and low tides is then at its maximum range, called a spring tide.

A density of 6g/cm3 is equivalent to Answer the question by selecting the correct response. 0.006kg/m3 0.06kg/m3 600kg/m3 6,000kg/m3

Option (D) is correct. The density in kg/m3 is calculated using the following expression. 6g / cm3 × 1 kg / 1,000g × (100cmx 1m)^3 = 6,000 kg/m3

2H2O(l)→2H2(g)+O2(g) If 9g of H2O decomposes according to the preceding chemical equation, how many moles of hydrogen gas are produced? Answer the question by selecting the correct response 0.5mol 1mol 2mol 4mol

Option (A) is correct. According to the balanced equation, 2 moles of H2O decompose to give 2 moles of H2. Since 9 g H2O × 1mol H2O / 18 g H2O = 0.5mol H2O, then 0.5 mol H2O × 2 mol H2O/ 2 mol H2 of hydrogen gas is produced.

The driver of a moving train always sounds its horn as the train approaches an intersection. As described by the Doppler effect, the sound heard by a stationary observer near the intersection will have a Answer the question by selecting the correct response. higher frequency than the sound heard by the driver longer wavelength than the sound heard by the driver larger amplitude than the sound heard by the driver greater speed than the sound heard by the driver

Option (A) is correct. As the train approaches, the sound heard by a stationary observer will have a higher frequency than the sound heard by the driver of the train. In other words, the pitch of the sound will increase as the train approaches and then decrease as the train moves away.

Water flowing from a pipe causes a paddle wheel to rotate. Which of the following devices could be attached to the rotating paddle wheel to convert its kinetic energy to electrical energy? Answer the question by selecting the correct response. A generator A transformer A photovoltaic cell A lever

Option (A) is correct. A generator transforms kinetic energy to electrical energy.

Few fish are found near a local sewage outfall, even though the area has a high level of nutrients and an abundance of floating algae. Which of the following most likely explains the low number of fish? Answer the question by selecting the correct response. Excessive bacterial growth has depleted the water of dissolved oxygen. The abundance of algae has increased the concentration of dissolved oxygen to a toxic level. Fish are outcompeted for resources by the algae at the sewage outfall. Fish are carnivores and avoid areas with algae.

Option (A) is correct. A high level of limiting nutrients, such as phosphates and nitrates, can lead to excessive growth of algae. Bacteria break down dead algae, depleting the water of oxygen in the process. The local fish are less likely to be adapted to water with a low concentration of oxygen.

Which of the following planets has the shortest period of revolution around the Sun? Answer the question by selecting the correct response. Mercury Earth Jupiter Neptune

Option (A) is correct. A planet's revolution is the amount of time it takes to orbit the Sun. Kepler's third law of planetary motion states that planets closer to the Sun experience shorter orbital periods. The closest planet to the Sun is Mercury, which has an orbital period of approximately 88 Earth days, the shortest of all planets in the solar system.

A teacher is searching for examples of reactions that will respond to a change in volume according to Le Châtelier's principle. Which of the following chemical equations could the teacher best use to represent a reaction at equilibrium that will favor the formation of additional product if the volume of the reaction mixture is decreased? Answer the question by selecting the correct response. PCl3(g)+Cl2(g)⇌PCl5(g) 2SO3(g)⇌2SO2(g)+O2(g) H2O(g)+Cl2O(g)⇌2HOCl(g) S8(s)+8O2(g)⇌8SO2(g)

Option (A) is correct. According to Le Châtelier's principle, for a gaseous equilibrium mixture, decreasing the volume of the reaction mixture will shift the equilibrium toward the side of the reaction with the smallest number of moles of gaseous molecules. In option (A), there are two moles of gaseous molecules of reactants and one mole of gaseous molecules of product, as represented in the equation. Therefore, decreasing the volume will favor the formation of additional product.

A pop. of butterfly species 1 occupies a habitat. Most members of the pop. have brown spots, and a few members have red spots. An unrelated species of butterfly, species 2, invades the habitat. All members of sp 2 have red spots. Members of both species are prey for the same predators. While species 1 butterflies are not toxic to the predators, SP 2 butterflies are toxic. After several years, most of the SP 1 population have red spots. Which of the following best explains this phenotypic change in the pop. of species 1? The pop. is undergoing directional selection because the proportion of individuals with red spots is increasing. The pop. is undergoing stabilizing selection because the number of individuals with brown spots is decreasing. The pop. is undergoing stabilizing selection because the pop. size is not changing. The pop. is undergoing disruptive selection because the original pop. was forced to change.

Option (A) is correct. Directional selection is a form of natural selection whereby one phenotype is favored over others, resulting in an increase in the frequency of the allele for that phenotype. In this example, the introduction of a second species of butterfly with red spots that is toxic to the same predators resulted in a higher proportion of individuals with red spots in the population of species 1. This type of evolutionary adaptation is known as mimicry.

Which of the following is a correct method of preparing a solution of a strong acid? Answer the question by selecting the correct response. Place some water into a flask, measure out the required amount of acid in a graduated cylinder, add the acid to the water, and add water until the correct overall volume is obtained. Measure out the required amount of water in a graduated cylinder, measure out the precise amount of acid in a graduated cylinder, and mix the two solutions in a beaker. Measure out the required amount of acid in a graduated cylinder, place acid in a flask, and add water until the correct overall volume is obtained. Measure out the volume of acid needed in a graduated cylinder, add the required amount of water, and mix.

Option (A) is correct. Dissolving a strong acid in water is a highly exothermic process. To prevent the splattering of a hot acidic solution, the measured acid should be slowly added to a volume of water. Additional water is then added until the desired overall volume of solution is obtained.

Experimental evidence supports the fact that most of the mass of an atom is contained in which of the following? Answer the question by selecting the correct response. The nucleus The electron cloud The sublevels The valence level

Option (A) is correct. Ernest Rutherford published results of his gold foil experiment in 1911. A beam of alpha particles was directed at a thin sheet of gold foil. Most of the particles passed through the foil, but some were reflected or deflected, providing experimental evidence that the atom has a relatively small nucleus that contains most of the mass of the atom.

Of the following substances, which has the lowest normal boiling point? Answer the question by selecting the correct response. H2 HI H2O NH3

Option (A) is correct. Hydrogen is a small nonpolar molecule. It has relatively weak London dispersion forces only and therefore a low boiling point. The other molecules have much stronger intermolecular forces in the liquid phase. H2O and NH3 have hydrogen bonding, and HI is a polar molecule.

Lactose intolerance occurs when a person cannot digest foods that contain lactose, such as milk and ice cream. Lactose belongs to which of the following groups of molecules? Answer the question by selecting the correct response. Carbohydrates Fats and oils Proteins Vitamins

Option (A) is correct. Lactose is a carbohydrate. Specifically, lactose is a disaccharide composed of the monosaccharides galactose and glucose.

Which of the following states the law of superposition? Answer the question by selecting the correct response. In an undisturbed section of strata, older rocks are found in lower positions. In an undisturbed section of strata, younger rocks are found in lower positions. Each section of strata must be compared to the other sections to establish relative age. The position of each strata cannot indicate relative age

Option (A) is correct. Nicolaus Steno, a Danish geologist, observed changes in a sequence of rock layers that became known as the law (or principle) of superposition. The law states that in a sequence of sedimentary rock layers, each layer of rock is older than the layer above it and younger than the layer below it. Superposition also can be applied to geologic events on Earth's surface, such as lava flows and ash layers from volcanic eruptions.

In an experiment, a student determines the heat of reaction for a certain reaction to ben−37.5kJ/mol. The accepted value for the heat of reaction is −55.8kJ/mol. Which of the following gives the percent error? (55.8 - 37.5 / 55.8) x 100% (55.8 - 37.5 / 37.5) x 100% (37.5 / 55.8) x 100% (55.8 / 37.5 ) x 100%

Option (A) is correct. Percent error is calculated by the following mathematical procedure. The absolute value of the fraction, accepted value minus experimental value, over accepted value, end absolute value, times 100%, equals, the absolute value of the fraction, 55.8 minus 37.5 over 55.8, end absolute value, times 100%, which equals 32.8% ∣∣∣Accepted value−experimental value / Accepted value∣∣∣ ×100% = ∣∣∣55.8−37.5/ 55.8∣∣ ∣×100% =32.8%

Which of the following statements could a student use to support a claim that ribosomes are not organelles? Answer the question by selecting the correct response. Ribosomes are not surrounded by a membrane. Ribosomes contain genetic material. Ribosomes are found in bacteria. Ribosomes act as catalysts.

Option (A) is correct. Ribosomes, which are composed of RNA and proteins, are not surrounded by a membrane. This characteristic distinguishes ribosomes from membrane-bound organelles.

A teacher selects the preceding diagram for a lesson on meteorology. Which of the following types of front is illustrated by the diagram? Answer the question by selecting the correct response. A cold front A warm front An occluded front A stationary front

Option (A) is correct. The diagram is a typical representation of a cold front, which is characterized by advancing cold air wedged under the warm air, forcing it aloft. As the warm air rises rapidly, water vapor will condense to form clouds, which quickly become large cumulonimbus clouds. These clouds often bring heavy but short-lived precipitation and thunderstorms.

AgNO3(aq)+NaCl(aq)→AgCl(s)+NaNO3(aq) For the precipitation reaction represented by the preceding chemical equation, the net ionic reaction is Answer the question by selecting the correct response. Ag+(aq)+Cl−(aq)→AgCl(s) NO3−(aq)+Na+(aq)→NaNO3(aq) Ag+(aq)+NO3−(aq)+Na(aq)+Cl(aq)→AgCl(s)+NaNO3(aq) Ag+(aq)+NO3−(aq)+Na+(aq)+Cl(aq)→AgCl(s)+NO3−(aq)+Na+(aq)

Option (A) is correct. The net ionic reaction shows only the ions that react to form the precipitate AgCl

23 11 Na→X+e−10 As represented by the preceding incomplete nuclear equation, a nuclide X is formed and an electron is emitted. Which of the following represents the nuclide X? Answer the question by selecting the correct response. M g with atomic number 12 and mass number 24Mg1224 N a with atomic number 11 and mass number 23Na1123 N e with atomic number 10 and mass number 24Ne1024 F with atomic number 9 and mass number 20F920

Option (A) is correct. The nuclide X is Mg with atomic number 12 and mass number 24, Mg 12-24 . The answer can be found by looking at the incomplete nuclear equation N a with atomic number 11 and mass number 23, reacts to produce, X with atomic number y and mass number z, plus an electron with left superscript 0 and left subscript negative 1 Na11-23→Xy-z + e−1-0 , in which y is the atomic number and z is the mass number, and then balancing the superscripts and subscripts. In the balanced nuclear equation, y minus 1 equals 11, y−1 = 11 and z plus 0 equals 24 z+0 = 24; hence, y equals 12 y = 12 and z equals 24; z = 24

The process of translation uses the nucleotide sequence in messenger RNA for the synthesis of which of the following? Answer the question by selecting the correct response. Proteins Lipids DNA Carbohydrates

Option (A) is correct. Translation refers to the synthesis of proteins based on codons, or sequential ribonucleotide triplets, present in an mRNA. A ribosome binds to an initiation codon of an mRNA, and tRNAs, carrying individual amino acids as dictated by the codon sequence, bind to sequential codons in the mRNA. The ribosome forms peptide bonds between the amino acids, and the amino acids are released from the tRNAs, which then dissociate from the mRNA and the ribosome.

Which of the following is an example of a parasitic relationship? Answer the question by selecting the correct response. Ticks attached to a white-tailed deer Nitrogen-fixing bacteria living in nodules on the roots of a bean plant Protozoans living in the intestine of an adult termite Algae living in the cytoplasm of an amoeba

Option (A) is correct. A parasitic relationship is one in which one organism benefits and the other is harmed. The ticks obtain nourishment from the blood they suck from the deer. The deer may be harmed if it loses too much blood, if too many ticks are attached, or if it contracts an infection from the ticks.

Which of the following statements about cancer is most likely true? Answer the question by selecting the correct response. The cells divide by meiosis instead of mitosis. The cells divide more rapidly than normal cells do. The cells skip all stages of interphase and go from one division to the next. The number of chromosomes in each new generation is twice that of the previous generation.

Option (B) is correct. A common characteristic of cancer cells is that they divide more rapidly than normal cells do. This situation is typically caused by mutations in DNA that affect the regulation of interphase and mitosis.

DNA synthesis occurs by semiconservative replication in which each strand serves as the template for the synthesis of a new strand. Which of the following characteristics of DNA is most important to this mechanism? Answer the question by selecting the correct response. DNA is composed of four different nucleotides. The two strands of a DNA molecule exhibit complementary base pairing. DNA is a helical molecule with a constant distance between each turn of the helix. The nucleotides of which DNA is composed lack the 2′-OH group present in ribose.

Option (B) is correct. A molecule of DNA is composed of two antiparallel strands of nucleotides; the strands are held together by hydrogen bonds between complementary base pairs on the two strands. During DNA replication, the two strands separate and a new strand complementary to each template strand is synthesized by DNA polymerases. Because nucleotides containing adenine (A) must pair with nucleotides containing thymine (T) and nucleotides containing cytosine (C) must pair with nucleotides containing guanine (G), only one possible nucleotide can be added opposite the nucleotide present on the template strand. Thus each template strand dictates the sequence of the new strand with which it will bind.

The mass percent composition of hydrogen in a certain hydrocarbon compound is 20%. Of the following assumptions, which could a student first make to correctly determine the chemical formula of the hydrocarbon? Answer the question by selecting the correct response. There are 2 grams of hydrogen in 8 grams of the hydrocarbon. There are 2 grams of hydrogen in 10 grams of the hydrocarbon. There are 2 hydrogen atoms in each molecule of the hydrocarbon. There are 2 hydrogen atoms for every 8 carbon atoms in the hydrocarbon.

Option (B) is correct. A student should assume that there are 2 grams of hydrogen in 10 grams of the hydrocarbon and that carbon accounts for the other 8 grams. Dividing 2 grams and 8 grams by the molar masses of hydrogen and carbon, respectively, reveals that the molar ratio of hydrogen to carbon is 3 to 1. The chemical formula of the hydrocarbon could be C2H6, since it has a ratio of 3 to 1.

In the last century, scientists began using which of the following technologies to a significant extent to study ocean floor topography? Answer the question by selecting the correct response. Radar Sonar GPS Satellite imaging

Option (B) is correct. Advances in sonar technology allowed scientists to do more extensive and detailed mapping of the ocean floor, particularly in deep water. The maps revealed the extent of the mid-ocean ridges and played an important role in the development of plate tectonic theory.

Brass is an alloy of copper and zinc in which the proportions of copper to zinc can vary. Which of the following is true about brass? Answer the question by selecting the correct response. Brass is a mixture, because it consists of more than one element. Brass is a mixture, because copper and zinc are not present in a definite ratio. Brass is a compound, because copper and zinc atoms share electrons. Brass is a compound, because copper and zinc combine in multiple proportions.

Option (B) is correct. Brass is a uniform solid mixture of the metals copper and zinc. The copper and zinc can be mixed in various proportions to produce brasses with different but generally metallic properties. Brass is not a compound, because when elements chemically combine, they typically combine in whole-number ratios, as described by the law of multiple proportions.

An individual with diabetes may have elevated blood sugar levels at various times throughout the day because of which of the following? Answer the question by selecting the correct response. Energy from cells in the digestive system is not available to digest the ingested food. Insufficient insulin is released in a negative feedback response that regulates blood sugar level. The rate at which body cells perform glycolysis is regulated by the time of day. Elevated blood sugar levels counteract low sugar levels in the cells of tissues.

Option (B) is correct. Diabetes occurs when the pancreas does not produce enough insulin in response to high blood sugar levels or the body does not respond properly to the insulin released.

Ball 1 has a mass of 4 kilograms4kg and is moving to the right with a speed of 5m/s . It undergoes a head-on, perfectly elastic collision with ball 2, which has a mass of 2kg and is at rest. Which of the following best describes the motion of the balls immediately after the collision? Answer the question by selecting the correct response. Ball 1 and ball 2 are stuck together and move to the right with a speed of 5m/s . Ball 1 is at rest and ball 2 moves to the right with a speed of 5m/s . Ball 1 and ball 2 move to the right with speeds of less than 5m/s . Ball 1 moves to the left and ball 2 moves to the right, both with speeds of less than 5m/s .

Option (C) is correct. In a perfectly elastic collision, momentum and kinetic energy are conserved. Because ball 1 is more massive than ball 2, both balls will move to the right at speeds less than 5 meters per second5m/s, with ball 2 moving faster than ball 1. If the balls have the same mass, or if ball 1 is less massive than ball 2, the motions described in option (B) and option (D), respectively, result.

Which of the following solutions is most resistant to a change in pH when a small amount of an acid or a base is added? Answer the question by selecting the correct response. 0.1 M HNO3 and 0.1 M NaNO3 0.1 M HNO3 and 0.1 M NaOH 0.1 M HC2H3O2 and 0.1 M NaC2H3O2 0.1 M Na2CO3

Option (C) is correct. A buffer solution is a solution that is resistant to changes in pH when a small amount of an acid or base is added. Buffer solutions are commonly prepared by mixing equal amounts of a weak acid and a soluble salt of its conjugate base as in option (C).

The distance between the adjacent nodes of a one-dimensional standing wave is 0.500m. If the frequency of the wave is 100Hz, then the speed of the wave is Answer the question by selecting the correct response. 25.0m/s 50.0m/s 100.0m/s 200.0m/s

Option (C) is correct. A wavelength is the distance between wave crests for a traveling wave, or twice the distance between adjacent nodes for a standing wave. Thus the wavelength λ is 1.000m. The frequency ff is 100Hz, which is equal to 100 cycles per second or 100s−1. The speed of the wave is equal to the frequency times the wavelength, or v equals f times lambda, which equals 100.0 s to the negative 1 power, end power, times 1.000 meter per second v= fλ = 100.0s^−1 × 1.000m/s

Of the following methods, which is best for determining the exact age of a particular fossilized animal? Answer the question by selecting the correct response. Noting how closely the fossil's shape resembles that of its relatives living today Noting what rock type the fossil was found in Obtaining a radioactively determined date from rock stratigraphically near the fossil Applying the principle of faunal succession, which places fossils in order of age

Option (C) is correct. Absolute age of a fossil is determined through radioactive dating. If there is an isotope inside a mineral in a rock that is radioactive, it will break down naturally into a lighter element called a decay, or daughter, product. This process occurs at a predictable rate, referred to as half-life, which is the time required for half an element's atoms (the parent) in a sample to change to the decay (daughter) product. Examining the decay-product (daughter-parent) ratio can be used to determine how old an object is.

The spring shown in the preceding diagram stretches 3cm when a mass of 4kg is suspended from it. How far will the spring stretch if a 12kg mass is suspended from the spring in place of the 4kg mass? (Assume that the elastic limit is not reached.) Answer the question by selecting the correct response. 4cm 6cm 9cm 11cm

Option (C) is correct. According to Hooke's law, the displacement of the spring from its equilibrium position depends linearly on the stretching force. Thus, increasing the force on the spring by a factor of three will increase the stretch of the spring by a factor of three, or 9 centimeters9cm .

Malaria, dengue fever, and West Nile fever are viral diseases transmitted by mosquitoes. Of the following actions, which will most likely reduce the likelihood of acquiring viral diseases spread by mosquitoes? Answer the question by selecting the correct response. Regularly treating hands with antibacterial soaps and hand sanitizers Taking antibiotics while traveling in regions with large populations of mosquitoes Using barriers such as mosquito nets and insect repellents Avoiding habitats with little to no surface freshwater

Option (C) is correct. An effective way of reducing the likelihood of acquiring a disease transmitted by mosquitoes is to avoid being bitten by using barriers such as mosquito nets and insect repellents.

A student observes that when N a 2 C O 3, solid,Na2CO3(s) is added to H C l, aqueousHCl(aq) , an exothermic reaction takes place. The student predicts that K 2 C O 3, solid,K2CO3(s) will also undergo an exothermic reaction with H C l, aqueousHCl(aq). The prediction is an example of which of the following? Answer the question by selecting the correct response. An observation A measurement An inference An analysis

Option (C) is correct. An inference is a conclusion based on observations and scientific reasoning. Because Na2CO3(s) and K2CO3(s) are composed of the CO32−, it can be inferred that both undergo similar reactions with HCl(aq) and that the reaction of K2CO3(s) with HCl(aq) is also exothermic.

The solubility of KCl at 40°C is 39g n 100g of water. If 82g of KCl are added to 200g of water at 40°C, which of the following is true at equilibrium? Answer the question by selecting the correct response. All of the KCl is dissolved, and the solution is saturated. All of the KCl is dissolved, and the solution is unsaturated. Most, but not all, of the KCl is dissolved, and the solution is saturated. Most, but not all, of the KCl is dissolved, and the solution is unsaturated.

Option (C) is correct. At 40°C , 78g of KCl are dissolved in 200g of water to produce a saturated solution. The remaining 4g of undissolved solid are in equilibrium with the saturated solution.

If the liquid level in a thermometer is approximately halfway between the markings for 21.4°C and 21.5°C, how should the temperature be recorded with the correct number of significant figures? Answer the question by selecting the correct response. 21°C 21.4°C 21.45°C 21.5°C

Option (C) is correct. For any marked measuring device, one place beyond the numerical place of the marking is estimated, and this determines the correct number of significant figures. If the thermometer is marked to 0.1°C , the hundredth place should be estimated and the temperature recorded as 21.45°C .

A flock of black-colored sheep was mated with a flock of white-colored sheep, and the first generation produced all black offspring. When these offspring interbred to produce a second generation, the ratio was approximately 75% black and 24% white. One of the offspring, however, appeared gray. Which of the following is the best explanation for the appearance of the gray sheep? Answer the question by selecting the correct response. The black allele was dominant over the white allele. A crossing-over event occurred between the black and white alleles during meiosis. A mutation resulted in less black pigment in the sheep's wool. The black and white alleles were codominant.

Option (C) is correct. The phenotypic ratio in the second generation suggests that the sheep in the first generation were heterozygous for color, with black being the dominant allele. This would mean that the sheep in the parent generation were homozygous for their respective colors. Based on the pattern of inheritance, it is most likely that a mutation is the cause for the appearance of the gray sheep.

Two species of paramecia thrive equally when grown separately in tanks under identical conditions. When equal numbers of species 1 and species 2 are added to a third tank and grown together under the same conditions, species 1 always grows to a much larger population size than does species 2. The species do not consume each other. This difference in growth is best explained by Answer the question by selecting the correct response. predation mutualism competition parasitism

Option (C) is correct. The scenario is best explained by competition between the two species of paramecia when grown in the same tank, with one species having an advantage over the other species under conditions where resources are limited.

Students learn that H C l, aqueous,HCl(aq) is a strong acid. Which of the following student claims indicates the best understanding of what is meant by the term "strong acid"? Answer the question by selecting the correct response. Aqueous solutions of HCl contain equal concentrations of H+(aq) and OH−(aq) HCl does not dissociate at all when it dissolves in water. HCl dissociates almost completely when it dissolves in water. HCl cannot be neutralized by a weak base.

Option (C) is correct. The strength of an acid is indicated by how much it dissociates when dissolved in water. Strong acids are acids that almost completely dissociate when dissolved in water.

Of the following taxonomic groups, which typically includes the smallest number of species? Answer the question by selecting the correct response. Class Domain Family Phylum

Option (C) is correct. The taxonomic ranking from most inclusive to least inclusive is domain, kingdom, phylum, class, order, family, genus, species. Of the options listed, family is the group that is typically expected to include the smallest number of species.

Plants that reproduce by making flowers and seeds are classified as Answer the question by selecting the correct response. conifers bryophytes angiosperms ferns

Option (C) is correct. The term "angiosperm" refers to a plant that produces seeds within an enclosure (the fruit) and is commonly called a flowering plant. Conifers are a type of gymnosperm, a group that reproduces by making unenclosed (naked) seeds but does not flower. Bryophytes, a collective term for nonvascular plants, reproduce by producing spores. Similarly, ferns reproduce only through the production of spores.

The force of gravity on Mars is approximately one-third that of Earth. How do an object's weight and mass on Mars compare to its weight and mass on Earth? Answer the question by selecting the correct response. The weight on Mars is the same, and the mass on Mars is the same. The weight on Mars is less, and the mass on Mars is greater. The weight on Mars is less, and the mass on Mars is the same. The weight on Mars is greater, and the mass on Mars is less.

Option (C) is correct. The weight of an object is equal to the force of gravity acting on the object; therefore, the weight of an object on Mars would be less than the weight of the object on Earth. The mass of the object does not depend on the location of the object; therefore, the object's mass would be the same on Mars and on Earth.

Which of the following best accounts for the fact that metals are good conductors of electricity? Answer the question by selecting the correct response. Valence electrons are transferred from one atom to another to form positive and negative ions. Valence electrons are shared between neighboring atoms only. Valence electrons are delocalized in a crystal lattice of positive ions. Polar covalent bonds form between the atoms.

Option (C) is correct. Valence electrons of metals are delocalized and held loosely in a crystal lattice of positive ions. The mobility of the electrons accounts for the electrical conductivity of metals.

A teacher is planning a unit on electricity. Of the following student activities, which could the teacher select to best help the students understand Coulomb's law? Answer the question by selecting the correct response. Students assemble both a series circuit and a parallel circuit using the same battery, two identical resistors, and the same type of wire and then measure the current in each circuit. Students build an electromagnet and count the maximum number of paper clips that can be picked up each time the number of turns of the wire around an iron nail is increased. Students use an online simulation that calculates the electrostatic force as the students vary the magnitude of two point charges and the distance between them. Students measure and compare the electrical conductivity of aqueous solutions of different ionic compounds with different known molarities.

Option (C) is correct. Coulomb's law quantifies the electrostatic force F between two charged particles, as represented by the equation F= K q1q2/r2 , where K is Coulomb's constant, q1 and q2 are the magnitudes of the charges, and r is the distance between the charges.

Which of the following statements refers to a plot of the surface temperature of stars versus their absolute magnitude and explains its importance to astronomers? Answer the question by selecting the correct response. Parallax helps astronomers determine the distances of stars from Earth. An absorption spectrum helps astronomers determine the compositions of stars. A star field helps astronomers identify the stars that compose a constellation. A Hertzsprung-Russell diagram helps astronomers determine the evolutionary stages of stars.

Option (D) is correct. A plot of the surface temperature of stars versus their absolute magnitude is called a Hertzsprung-Russell diagram. The location of a star within certain regions of the diagram provides information about the evolutionary stage of the star.

To test the effects of cadmium on the germination of lima bean seeds, a researcher planted 100 lima bean seeds in potting soil in separate pots and applied 100mL of a cadmium solution to each pot. Which of the following is the best control group? Answer the question by selecting the correct response. 100 pea seeds planted in potting soil in separate pots with 100mL of the cadmium solution applied to each pot 100 lima bean seeds planted in potting soil in separate pots with no solution applied 100 pots containing potting soil with 100mL of the cadmium solution applied to each pot 100 lima bean seeds planted in potting soil in separate pots with 100mL of water applied to each pot

Option (D) is correct. A typical control group has conditions identical to the experimental group except for the treatment, or independent variable, being tested. In this experiment, it is the effect of cadmium on germination that is being tested, so instead of a cadmium solution, a control group of 100 lima beans planted in potting soil in separate pots should have 100 milliliters100mL of water applied to each pot.

In a chain of islands, closely related bird species occupy different islands. The species share a common ancestor that inhabits the mainland. Which of the following was the most likely mechanism of speciation? Answer the question by selecting the correct response. Coevolution Gene flow Spatial isolation Adaptive radiation

Option (D) is correct. Adaptive radiation is the process by which a population from an ancestral species relocates to a new environment, occupying a variety of niches. Each niche has different selective pressures, leading to the emergence of new species. The finches of the Galápagos Islands are a well-known example of adaptive radiation.

If a radioisotope has decayed for 5 half-lives, what fraction of the original amount of the radioisotope remains? Answer the question by selecting the correct response. 1/5 1/10 1/16 1/32

Option (D) is correct. After one half-life has passed, half the radioisotope remains in the sample; after the second half-life has passed, one-quarter remains; and so on. The fraction of a radioisotope that remains in a sample is calculated by the fraction one half raised to the x power(12)x(12)𝑥 , where x is the number of half-lives that have passed. Thus, the fraction one half raised to the 5 power, equals one half times one half, times one half, times one half, times one half, which equals the fraction 1 over 32 (1/2)^5 = 1/2×1/2×1/2×1/2×1/2=1/32

the preceding graph represents a linear motion of an object during 20 seconds of travel. During which 5-second interval does the object travel the longest distance? Answer the question by selecting the correct response. A B C D

Option (D) is correct. Based on the graph, the magnitude of velocity for the 5-second interval labeled D is 15m/s, which is higher than the velocities for the other intervals. The object would travel 75m during the 5-second interval.

Which of the following actions has led to a significant reduction in acid precipitation in the United States? Answer the question by selecting the correct response. Capturing methane formed by anaerobic decomposition in landfills Using alternatives to chlorofluorocarbons in aerosol cans Shutting down and replacing older nuclear power plants Installing devices to reduce sulfur dioxide emissions from coal-burning plants

Option (D) is correct. Burning of fossils fuels, such as coal, produces sulfur and nitrogen oxides, which may react with water in the atmosphere and lead to acid precipitation. Installation of devices that remove these pollutants from industrial exhaust before it is released into the atmosphere has greatly reduced the amount of acid precipitation in the United States.

A 10 kilogram10kg cart is rolling along the surface shown in the preceding figure. What is the minimum kinetic energy of the cart at the base of the hill if it is going to be able to roll to the top of the hill? (Assume g=10m/s2.) Answer the question by selecting the correct response. 4 joules 10 joules 40 joules 400 joules

Option (D) is correct. By energy conservation, the sum of the cart's kinetic energy and potential energy is a constant (assuming negligible energy loss due to friction and air resistance). As the cart moves up the hill, its kinetic energy will decrease and its potential energy will increase. If the cart just reaches the top of the hill, then the cart will be at rest at the top of the hill and will have only potential energy at that point; that is, its initial kinetic energy at the base of the hill will have been converted entirely into potential energy at the top of the hill. Thus, the minimum kinetic energy of the cart is 10kg×10m/s2×4.0m = 400 joules

Under which of the following circumstances would a population of an animal species be expected to increase at the greatest rate? Answer the question by selecting the correct response. New predators are introduced into the habitat. The habitat is experiencing a prolonged drought. The population has reached its carrying capacity. The population size equals half the carrying capacity of the habitat.

Option (D) is correct. Carrying capacity is defined as the maximum population size that a particular environment can support based on available resources, including food, shelter, and sites in which to nest or hide from predators. If the population is at half the carrying capacity of the habitat, the population will most likely continue to increase in size.

An individual with cri-du-chat syndrome possesses a chromosome 5 that is missing a segment of its short arm. This is an example of which of the following types of mutation? Answer the question by selecting the correct response. A missense mutation A frameshift mutation An inversion A deletion

Option (D) is correct. Deletion is a type of mutation that occurs when part of a chromosome is missing or deleted during DNA replication.

Of the following substances, which is most strongly attracted to a magnet? Answer the question by selecting the correct response. Aluminum Magnesium Gold Iron

Option (D) is correct. Ferromagnetic substances will be most strongly attracted to a magnet. Of the four elements listed, only iron is ferromagnetic.

Which of the following terms is used to correctly describe the current model of the solar system? Answer the question by selecting the correct response. Circumpolar Epicyclic Geosynchronous Heliocentric

Option (D) is correct. Heliocentric is the term used to describe the current model of the solar system, with the Sun at the center and the planets revolving around the Sun.

As part of a unit on engineering design, students build three cars that each have a spring-loaded mousetrap on a base with four wheels. The students test the effect of the arm length and rear wheel diameter on car performance. The arm, which is connected directly to the mousetrap, and the rear wheels are components of the system that propels the car. Based on the data in the preceding table, if the design criterion is to maximize the distance the car travels, which TWO of the following should the students consider doing to optimize the design? Answer the question by selecting the correct responses. Increasing the arm length Decreasing the arm length Increasing the wheel diameter Decreasing the wheel diameter

Options (A) and (C) are correct. Based on the data, increasing the length of the arm and the diameter of the rear wheels both resulted in an increase in the distance the car traveled. Students should consider building and testing additional cars that are based on car 2, which traveled the farthest, and that incorporate a longer arm or larger wheels.

According to the stellar evolutionary model, when the Sun evolves from a yellow dwarf into a red giant, it will begin fusing hydrogen in a shell surrounding its core and then helium in the core. Which TWO of the following best describe the overall changes in the physical characteristics of the Sun that will result as it becomes a red giant? Answer the question by selecting the correct responses. Its diameter will increase. Its mass will increase. Its surface temperature will increase. Its luminosity will increase.

Options (A) and (D) are correct. When the Sun evolves into a red giant, it will expand to many times its current diameter and its luminosity will be greater than it is now. Its surface temperature will be lower, thus its red color. The Sun will continue to lose mass through the solar wind and, to a lesser extent, by the conversion of mass to energy through nuclear processes.

Of the following ways to produce electricity for a certain region using turbine-driven generators, which THREE involve the use of a renewable resource? Answer the question by selecting the correct responses. Burning regionally sourced waste wood at a local power plant Combusting heating oil in an internal combustion engine at a local power plant Rotating rotor blades at wind farms situated on several local mountains Releasing water trapped behind regionally situated dams

Options (A), (C), and (D) are correct. Wood, wind, and flowing water are renewable resources because they can be quickly replenished. Heating oil and other fossils fuels are nonrenewable resources because they take a very long time to form and are not quickly replenished.

A teacher is searching for images to include in a presentation for a lesson on weathering. To illustrate chemical weathering, the teacher could select images of which TWO of the following? Answer the question by selecting the correct responses. A granite outcrop that is covered with sheets of fractured rock caused by exfoliation A limestone cavern formed by the dissolution of calcite by water flowing underground A rock with rust stains on its surface from the oxidation of iron-containing minerals A seaside cliff that has been undercut as a result of abrasion by sediments transported by waves

Options (B) and (C) are correct. Chemical weathering occurs when water, gas, and acid interact with minerals in rocks, leading to various chemical reactions that change the rocks' composition. Dissolution occurs when atmospheric carbon dioxide dissolves in rainwater, producing a weak acid known as carbonic acid. Carbonic acid is effective at dissolving rocks, especially those containing calcite, such as limestone and marble. Oxidation occurs when atmospheric oxygen reacts with various metals in minerals to create a new oxide mineral. Rusting is the better-known term for this process.

Which TWO of the following statements explain how energy is most directly provided in eukaryotic cells for the active transport of ions across the plasma membrane? Answer the question by selecting the correct responses. Messenger RNA is transcribed from DNA in the nuclei, releasing energy. Vacuoles store fat to provide energy for active transport. Metabolism of sugars provides energy to synthesize ATP. ATP molecules synthesized in the mitochondria are hydrolyzed, releasing energy.

Options (C) and (D) are correct. Active transport refers to moving a substance such as an ion against its gradient (often a concentration gradient) from lower to higher. This requires a source of energy. Often in eukaryotic cells, as ATP is hydrolyzed to A D P plus P sub iADP+Pi, energy is released. Cells obtain the energy to initially synthesize ATP through metabolism of foods such as sugar. ATP is formed through the pathways of glycolysis and the Krebs cycle but especially as a consequence of energy transfers during redox reactions along electron transport chains in the mitochondria.