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ACT Science 2, Set 2
Answers & Explanations
1. B Amount of helium in the balloon. The beginning of the passage states that the number
of moles is held constant. The pressure,
temperature, and volume vary at times
throughout the three experiments.
2. G Experiment 1. This experiment is performed
while leaving the ambient air pressure constant at 1 atmosphere, as noted under Table 1.
The pressure varies in experiments 2 and 3.
3. D Pressure and Volume in Experiment 2. In
experiment 2, pressure and volume have an
inverse relationship while temperature is
held constant in the ideal gas law equation.
In other words, as volume increases, the pressure decreases. The graphs for experiments
#1 and #3 are linear graphs with positive
slopes.
4. F 0.763 Liters. The answer for this question
can be obtained by two different means.
Referencing Table 1, the volume is .775 L at
303 K and .750 L at 293 K. The question
asks for the volume at 298 K. Since 298 K is
exactly in the middle of 293 K and 303 K,
then you can find the average of the volumes,
which is .763 L. You can also plug in the
values in from the table and using the equation given in the question. The answer is determined as follows: V1/T2 = V2/T1 or (.700
L)(298 K) = V2(273 K). V2 = .763 L.
5. C To prevent the volume from increasing. The
woven mesh is not stretchy like the balloon
membrane. The scientist puts the mesh
around the balloon to ensure that the volume
of the balloon will not increase. As a result,
the pressure in the balloon will increase while
the temperature increases because the mesh
will not allow the balloon membrane to expand.
6. J
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The cooler air temperature in the morning
caused lower pressure in the tires. By looking at the results of experiment 3, the pressure decreases with a decrease in temperature
when the volume is held constant. The volume of the air in a car tire does not change.
Therefore, when the temperature is cooler in
the morning, the pressure will be less too.
7. C Experiment 3. See explanation above.
8. F The species that are the most endangered all
have high numbers for ecological distribution
while their numbers for the other categories
are not necessarily high.
9. B It has the highest score, making it the most
endangered.
10. G The species with the highest total score represent the most endangered, so though N. Petersii has a higher ecological distribution score than N. Ocelloscapilans, ultimately N. Ocelloscapulans has a higher total score, and is therefore more endangered.
11. A Boltioglossa decora has some of the highest scores possible for the locations in which it is located and ecological distribution. For this chart, higher numbers mean more endangered.
12. J The score for B. carri for ecological distribu
tion is 8 while the score for B. conanti for
ecological distribution is 7.
13. A Species A. This species has the highest spe
cific gravity, making it the thickest species,
and the highest glucose levels, making it the
sweetest species.
14. J Increases only. The species with a higher
concentration of glucose also have a higher
specific gravity.
ACT HOMEWORK SCIENCE 2, SET 2
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15. D The November species from species D. The
highest water content is likely to be found in
the sample with the lowest specific gravity,
because that means its density is closest to
water.
20. J Looking at the chart with experiment 3, there
are some metals that go down by 0.1 while
some go down 0.7. How much a metal ac
cepts lubrication depends on the metal’s
properties.
16. H The November sample from species D. This
sample has the lowest specific gravity, and
therefore the lowest weight relative to water.
21. A This will determine, much more than the
other answers, where the best materials for
the ball bearings will be.
17. D No, because there is no relationship between
sap sample volumes and color value. While
some of the samples with a high volume had
darker colors than those with less volume,
there is not a clear pattern to support the hy
pothesis.
22. F It has the lowest coefficient of them all.
18. F Species A. The sap color is within the ex
pected range for both species A and C. How
ever, only species A demonstrated a specific
gravity as high as 3.732.
19. C The passage provides no information
regarding the hardness of the alloys nor about how they can be determined.
23. A This does not affect the coefficient, which is
the same for all of the metal, regardless of
how much is present.
24. H Brass has much lower numbers than lead
when used with alloy B.
25. D Relative roughness or smoothness would
have a lot to do with the friction coefficient.
The more rough a material is, the less it is go
ing to slide.
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