ACT science practice test 5

Directions: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

You are NOT permitted to use a calculator on this test.


Organic compounds are molecules that frequently contain carbon (C), hydrogen (H), and oxygen (O) joined together by covalent bonds (symbolized by straight lines in chemical notation). As the number of bonds to oxygen atoms increases in a carbon chain, the overall molecule is increasingly oxidized. For example, aldehydes are more oxidized than alcohols, which are more oxidized than alkanes as shown in Table 1. The melting points of these compounds are listed in Table 2, and their viscosities (resistance to flow, or "stickiness,") are listed in Table 3.

1. Which organic compounds in

Table 2 are solids at 215 K?

A. All alkanes, alcohols, and aldehydes with 5 carbons or fewer.
B. Alcohols and aldehydes with 6 or more carbons and octane.
C. The 4- and 5-carbon alcohols and aldehydes, and all alkanes with 7 or fewer carbons.
D. The 5-carbon pentane and pentanol compounds and the 4-carbon butane, butanol, and butanaldehyde.

2. According to

Tables 1 and

3, which organic compound has the highest viscosity?

F. Octanol
G. Octanaldehyde
H. Hexanol
J. Butane

3. According to

Table 3, how do the different types of 5-carbon molecules differ with respect to their viscosity?

A. The alkane has a higher viscosity than the aldehyde and the aldehyde has a higher viscosity than the alcohol.
B. The alkane has a higher viscosity than the alcohol and the alcohol has a higher viscosity than the aldehyde.
C. The alcohol has a higher viscosity than the alkane and the alkane has a higher viscosity than the aldehyde.
D. The alcohol has a higher viscosity than the aldehyde and the aldehyde has a higher viscosity than the alkane.

4. For each type of organic compound, what is the relationship between the length of the carbon chain to the melting point and viscosity? As the number of carbons in the chain increases, the melting point:

F. decreases and the viscosity decreases.
G. increases and the viscosity increases.
H. increases but the viscosity decreases.
J. decreases but the viscosity increases.

5. According to

Table 2, the difference in melting point between an alkane and an alcohol with the same number of carbons is approximately how much?

A. 25 K
B. 35 K
C. 45 K
D. 65 K

A mass suspended by a lightweight thread and swinging back and forth approximates the motion of a simple gravity pendulum, a system in which gravity is the only force acting on the mass, causing an acceleration of 9.8 m/sec2. The time to complete one cycle of swinging back and forth is the period and is inversely related to gravitational acceleration.

Using the same type and length of thread, 2 cubes were suspended, lifted to the same starting angle, and let go. The amount of time required for each pendulum to complete one swinging cycle (1 period) was recorded with a timer capable of reading to the nearest 0.01 sec. The measured times were used to calculate acceleration.

Experiment 1

A cube of lead (11.3 grams) and a cube of tin (7.4 grams) were suspended from a 0.5 m length of thread. Both cubes had the same length. (Note: A cube's volume is proportional to its length cubed; its surface area is proportional to its length squared.) The cubes were set in motion from a fixed starting angle, and the period for each was recorded.

The average periods were 1.46 sec and 1.48 sec for the lead and tin cubes, respectively. The average accelerations were 9.3 m/sec2 for lead and 9.1 m/sec2 for tin.

Experiment 2

The same procedures used in Experiment 1 were repeated using a thread length of 1.0 m and the same fixed starting angle. Results were recorded in Table 2.

The average periods were 2.06 sec and 2.09 sec for the lead and tin cubes, respectively. The average accelerations were 9.3 m/sec2 for lead and 9.0 m/sec2 for tin.

Experiment 3

Given the results of the first 2 experiments, the accuracy of the timer was tested. The procedures of Experiment 1 were repeated using only the lead cube. The trials were recorded on digital video at 100 frames per second. The video was then reviewed to obtain precise measurements of the period for each trial and results are shown in Table 3.

The average period recorded in Table 3 was 1.47 sec.

6. To demonstrate that a pendulum’s acceleration is reduced by drag force from air resistance, which additional experiment can be performed in addition to those in the passage?

F. The cubes are suspended by 0.5 m and 1 m springs and set in motion by extending the spring 9.8 cm and letting go in a vacuum chamber with no air pressure.
G. The cubes are suspended by 0.5 m and 1 m threads and set in motion from the same starting angle in a vacuum chamber with no air pressure.
H. The cubes are suspended by 0.5 m and 1 m springs and set in motion by extending the spring 9.8 cm and letting go in a vacuum chamber at 1 atmosphere of pressure.
J. The cubes are suspended by 0.5 m and 1 m threads and set in motion from the same starting angle in a vacuum chamber at 1 atmosphere of pressure.

7. In Experiment 1, could a timer that reads to the nearest second be used to obtain similar results, and why?

A. No, because the period of both pendulums was between 1 and 2 seconds.
B. No, because the pendulums would have traveled farther in 1 second than they did in 1 period.
C. Yes, because the period of both pendulums was approximately 1.5 seconds.
D. Yes, because the pendulums would not have traveled as far in 1 second as they did in 1 period.

8. The results of the experiments indicate that forces other than gravity are acting on the pendulums because the calculated values of acceleration were:

F. the same for pendulums of different lengths.
G. the same for cubes of different mass.
H. lower than the expected 9.8 m/sec2 from gravity alone.
J. greater than the expected 9.8 m/sec2 from gravity alone.

9. Based on the passage, if a tin cube is suspended from a 2.0 m thread and set in motion multiple times from the same starting angle, the average measured period will most likely be:

A. less than 1.48 sec.
B. approximately 1.48 sec.
C. approximately 2.09 sec.
D. greater than 2.09 sec.

10. In Experiment 2, if an additional trial were conducted using the lead cube, the cube’s measured period would most likely be nearest:

F. 1.90 sec.
G. 2.05 sec.
H. 2.15 sec.
J. 2.20 sec.

11. Experiments 1 and 2 were conducted using lead and tin cubes most likely to determine whether a pendulum’s period was altered by the material attached to the string and the cube’s:

A. length.
B. surface area.
C. starting angle.
D. mass.