Answer Key - Science
ScQ1-Answer: The best answer is B. The information in the diagram shows identical levels of gas molecules at identical temperatures; in this case, 20°C. Between the two containers, there is an obvious differential in size, but the given information also shows a difference in atmospheric pressure inside the containers. With other factors remaining equal, the inference is that amounts of gas in a smaller volume (as shown on the left) will experience a greater gas pressure than identical amounts placed in a larger container. Since the temperature is the same in both containers, options A, C, and D are automatically eliminated, leaving only option B. Thus, B is the correct answer.
ScQ2-Answer: The best answer is C. As demonstrated by the containers in the diagram, when temperature and mass are kept constant, the pressure of a gas contained within a closed area will rise as the volume decreases, and by the same token, the pressure will fall as the volume increases. Since the relationship is not dependent on both qualities exhibiting the same trend-i.e. as one rises, so does the other-the relationship is not direct, which eliminates option A. Because there is no precise measurement of the volume of the containers or their differences, there is insufficient data to determine if the relationship follows a mathematical progression, which eliminates options B and D. However, the observation that as one rises the other falls fits the standard definition of inverse, making option C the correct choice.
ScQ3-Answer: The best answer is D. Coulomb's law refers to the relationship between the magnitudes of point electric charges and their distance from each other; since the variables under discussion in this example are volume and pressure, option A can be eliminated. Newton's second law defines the relationship between rate of change in momentum and the force applied to a body, which eliminates option B. Ohm's law defines the relationship between current, potential and resistance in a circuit, which eliminates option C. Only Boyle's law, which defines the relationship between volume and pressure of a gas in an environment where temperature and mass are held constant, address the diagram, and thus D is the correct answer.
ScQ4-Answer: The best answer is B. In order to reach a constant value derived from a relationship between the pressure and volume variables, the expression must be made in terms of the constant value; in other words, the relationship that creates the constant value must be expressed in those terms, expressing k as the result of the variables and an operator. Therefore, options A and C can be dismissed, as they do not express the equation in terms of k. Given that the relationship between p and V is an inverse relationship (i.e. as one shrinks, the other expands), option D would be less likely to adequately express that, as the ratio between the constant and the variables would vary too greatly for different values of p and V. Only option B, which keeps the ratio between the variables constant, adequately expresses the relationship, making B the correct choice.
ScQ5-Answer: The best answer is D. The diagram shows an object in fluid, which is not creating low-pressure areas around it, which eliminates option A. Similarly, a whirlpool effect is not being displayed either, which eliminates option B. While compression is a part of what is being displayed in the diagram (it can be considered to be what is happening at the leading edge of the object in the fluid), it is secondary to the primary forces here, and is not of enough merit to be listed separately; thus, option C is eliminated. The upward force on the object is countermanding gravity, and that force in fluid is buoyancy, making option D the correct answer.
ScQ6-Answer: The best answer is D. In order to calculate the force exerted on the object by the fluid, the amount of fluid displaced by the object needs to be determined. This is done by determining the volume of the object, and then multiplying it by the density of the fluid, which yields the total displacement. However, the buoyant force must overcome the acceleration of gravity in order to keep the object afloat, so in addition to the force of the fluid acting upon the object, the acceleration of gravity must also be considered. Therefore, the fluid displacement must be combined with the acceleration of gravity in order to completely calculate the buoyant force; since only option D lists all three factors, D is the correct answer.
ScQ7-Answer: The best answer is C. In order to calculate the force exerted on the object by the fluid, the amount of fluid displaced by the object needs to be determined. This is done by determining the volume of the object, and then multiplying it by the density of the fluid, which yields the total displacement. As in the previous question, the force of gravity must be considered; however, since gravity acts in a downward direction, the buoyant force acts in an upward direction, and therefore must be assigned a negative number to reflect its opposite orientation. Thus, while the absolute value would be derived by using option D (options A and B are patently incorrect, as explained in the first part), the correct value reflecting the buoyant force's opposite orientation to gravity is given using option C.
ScQ8-Answer: The best answer is B. Remember that the formula for buoyant force if F = -pVg, where p is the fluid density, V is the volume of the object and g is the force of gravity (given a negative number because buoyant force acts upwards). The boxes are identical in mass, and the fluid has the same density, so neither of those measurements will change. However, the first box has twice the volume of the second, which means it displaces twice the fluid and therefore has twice the buoyant force acting upon the same mass as the second box does. Thus, the second box only has half the buoyant force acting on it as the first box, yet has the same mass. As a result, the second box will most likely sink due to the reduction in buoyant force, making option B the correct choice.
ScQ9-Answer: The best answer is C. The boiling point of water is 100°C (212°F), so if equal volumes of the liquids have heat applied to them at the same rate at the same time, the liquids with lower boiling points would logically start boiling first. Liquid S has a boiling point of 160.4°C (320.7°F), so options A and D are automatically eliminated. Liquid T has an even higher boiling point of 300°C (572°F), so option B can be eliminated as well, leaving option C to consider. Since liquids Q and R both have boiling points less than 100°C, they would both boil before the water does, and so option C is the correct choice.
ScQ10-Answer: The best answer is D. Of the three options listed, Q has a density greater than that of water, and since all the listed options are insoluble in water (meaning they will not break down in the water), Q would sink to the bottom of the flask due to its greater density. Thus, options A and C are eliminated automatically. Both liquids S and T, however, possess lesser density than water, so they would essentially float on top of the water. Since option B lists only one of the lighter density materials, it can be eliminated from consideration. Only option D correctly lists both lighter-than-water fluids, making D the correct answer.
ScQ11-Answer: The best answer is B. While the exact properties of each liquid are not given full description in the chart, a general idea is given for each. Option A can be eliminated immediately, as it is explicitly identified as a nonflammable compound, meaning it will not catch fire if heat or an open flame is applied. While options C and D are not explicitly identified one way or the other as flammable or not, it is reasonable to assume that their flammability is not as high as with other compounds, as care was made to identify that property for other liquids. However, option B is explicitly identified as being a flammable compound, and furthermore, is a colorless compound like option A, possibly increasing chances for confusing the two. Based on the information given in the chart, option B is the correct answer.
ScQ12-Answer: The best answer would be C. Given the requirements of the liquid relative to the liquids on the chart, option A can be eliminated immediately, as it has a density greater than water. Of the remaining choices, option B can also be eliminated, as its boiling point is below that of water. Finally, since a liquid with a strong odor is needed, option D can be eliminated, as it not only does not have an identified strong odor, but it is also an oil at normal lab conditions, which is likely to have a higher viscosity than is needed for most experiments. Therefore, option C is the only choice that meets all three requirements; thus, C is the correct answer.
ScQ13-Answer: The best answer is A. As displayed on the graph, most of the species populations had periods of greater numbers, usually followed by die-offs until a stable level was reached or, in some cases, extinction. Option B is unsuitable for this exact reason; the dinosaurs population reached its greatest numbers in the Jurassic period, then gradually fell until extinction, showing too much variance to be the answer. Snakes experienced a greater level of variation, which makes option C incorrect, and crocodilians, despite having a stable population for most of their measured length, experienced a population jump in the Tertiary and Cretaceous periods that disqualifies option D. Only turtles, whose population levels remain almost perfectly flat into the Permian period, show the least amount of variation, making option A the correct answer.
ScQ14-Answer: The best answer is B. While all species listed had some presence in the Triassic period, three of the five species on the chart ended there, and the population spread for all but dinosaurs was minimal, so option A is not suitable. Dinosaurs were not present in the Quaternary period, so option C is not correct. Since only turtles and dinosaurs had presence in the Permian period, option D is not correct either. Only in the Cretaceous period, where all five listed species had presence and three of them were at or near their greatest numbers, does the graph meet the stated goal; thus, option B is the correct answer.
ScQ15-Answer: The best answer is D. A quick glance at the chart shows that of the species listed, turtles and crocodilians were fairly flat at lower numbers throughout the time periods measured on the graph, and dinosaurs had smaller growth curves overall than snakes and lizards, which had the most significant numbers of any species listed, regardless of which time period is being examined. Therefore, options A and C can be automatically eliminated from further consideration. Upon examination of the graph, lizards clearly have greater numbers than snakes, as shown by the graphic distribution through the Quaternary and Tertiary periods, which automatically eliminates option B from consideration. Thus, option D is the correct answer.
ScQ16-Answer: The best answer is B. While all the listed species existed in the Jurassic, a look at the chart shows that all of them continued on into at least one more period, thereby eliminating option A from consideration. By the Permian period, only two species had continued on-turtles and dinosaurs-which eliminated option C from further consideration. By the Pennsylvanian period, which followed the Permian period, only dinosaurs were left according to the graph, so option D is not suitable. Despite the miniscule extent of three of the five listed species, all five did have durations in the Triassic period according to the graph, so therefore only option B is the correct answer.
ScQ17-Answer: The best answer is A. Based on the information in the chart, a tree grown in a normal atmospheric mixture took 18 days to shed all its leaves, while a tree grown in a CO2 enriched atmosphere took a total of 26 days to shed all its leaves. Simple subtraction shows that this is an 8-day difference between the two, and in order to find the percentage, the difference must be divided by the original time period. Thus, 8 ÷ 18, which can be expressed as 8/18 or, after simplifying, 4/9, or 0.4444, which gives a value of 44%. Therefore, the increase in time to shed all leaves resulting from a CO2 enriched atmosphere is 44%, which means option A is the correct answer.
ScQ18-Answer: The best answer is C. A quick glance at the chart shows that the control atmosphere led to a total time of 18 days, which was less than at least one term but longer than others, so option A can be eliminated. As demonstrated in the previous question, CO2 actually increased the length of time to shed leaves to 26 days, so option B can be eliminated. The CO2 + O3 mixture did substantially decrease the total shed time to 10 days, but as the chart shows, using the O3 mix cut it to three days, the lowest value on the list. Thus, option D can be eliminated, leaving option C as the correct answer.
ScQ19-Answer: The best answer is D. As shown on the chart, the shortest period of time for shedding leaves was three days using O3 as an atmospheric additive. The longest period of time was 26 days, using CO2 as an atmospheric additive. Since the only measures needed to determine the total variance are the high and low values, the other two measurements can be ignored for this determination. Thus, the total time variance would be the difference between the longest period for shedding leaves measured on the chart and the shortest period measured on the chart. Simple subtraction yields the result, which is 26 days minus 3 days, or 23 days total. Thus, option D would be the correct answer.
ScQ20-Answer: The best answer is C. Mitosis, or the process of cell division, is related to virtually all processes performed by trees, but is too general to fit within the scope of this experiment, thus eliminating option A. Likewise, option D can be eliminated, as replication is another process that is too general to fit within the scope of the experiment. Respiration is superficially a good fit for this experiment, but with respect to trees, it is a subcomponent of a larger process of photosynthesis, which directly affects the life cycle of leaves; it controls the coloration, functionality and point at which the leaf falls, making it a far better choice in terms of the experiment. Thus, option B is discarded, leaving option C as the correct answer.
Last Updated: 02/23/2013