ACT science practice test 72

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.

Tornado intensity is commonly estimated by analyzing damage to structures and then correlating it with the wind speed required to produce such destruction. This method is essential to assigning tornadoes specific values on the Fujita Scale (F scale) of tornado intensity (see Figure 1).


Figure 1

A tornado is formed when the following occurs: (1) warm, moist air rises into cool, dry air; (2) when the barrier is breached, a bulge of warm, moist air expands and condenses to form a cloud; (3) as air moves upward, the resulting instability creates a spiral of air called a mesocyclone; (4) cold air moves downward and rain falls as the cloud becomes a supercell; (5) cool, moist air from rain cycles back into a cloud, forming a spinning wallcloud; and (6) horizontal spiraling wind “tubes” are pushed upward by warm, moist air, forming a tornado. (See Figure 2.)


Figure 2

The United States has the most tornadoes of any country, and most of these tornadoes form in an area of the central United States known as “Tornado Alley.” Figure 3 displays a geographical (state-by-state) breakdown of the occurrence of tornadoes in the United States in 2005.


Figure 3

1. In Figure 2, the tornado is labeled with which number?

A. 1
B. 3
C. 5
D. 6

2. A tornado with an intensity of F4 on the Fujita Scale could have winds of which of the following speeds?

F. 70 mph
G. 155 mph
H. 190 mph
J. 210 mph

3. Which of the following does NOT precede the formation of a mesocyclone?

A. Warm air flowing upward
B. Cool air forming a spinning wall-cloud
C. Cloud formation
D. Moist air condensing

4. Based on the data provided in Figure 3, which of the following states can be inferred to be part of “Tornado Alley?”

F. Texas
G. Florida
H. Michigan
J. Washington

5. If the wind speed of a tornado was unknown, but it was observed that several brick buildings in the area sustained minor damage, what value would the tornado be assigned on the F scale?

A. F0
B. F1
C. F2
D. F3

Acid deposition delivers acids and acidifying compounds to the Earth’s surface. Once on the surface, they move through soil, vegetation, and surface waters and, in turn, set off a cascade of adverse ecological effects. Acid deposition occurs in three forms: wet deposition, which falls as rain, snow, sleet, and hail; dry deposition, which includes particles, gases, and vapor; and cloud or fog deposition, which occurs at high altitudes and in coastal areas. Acid deposition is comprised of sulfuric acid, nitric acid, and ammonium derived from sulfur dioxide (SO2), nitrogen oxides (NOx), and ammonia (NH3). Sulfuric and nitric acid lower the pH of rain, snow, soil, lakes, and streams.


Study 1

A specially designed collection bucket was used to gather rain samples. The collector opened automatically during wet weather, allowing the precipitation to fall into the collection bucket, and then closed as soon as the precipitation stopped. The sample was then taken to a laboratory, where it was weighed and its acidity was measured. Finally, the concentrations of important inorganic chemicals found in the precipitation were analyzed. The results are shown in Table 2.

Table 2


Study 2

Another study was done to compare the average pH of precipitation across various months. The same procedure was used as in Study 1, and the results are shown in Table 3.

Table 3


6. It is known that precipitation with a higher concentration of chlorine (Cl) does more damage to bodies of water than precipitation with a lower concentration of Cl. Based on this information, which sample tested in Study 1 would cause the most harm to rivers?

F. Sample 1
G. Sample 2
H. Sample 3
J. Sample 4

7. Based on the results of Study 2, it can be concluded that the deposition is least acidic during which season?

A. Spring
B. Summer
C. Fall
D. Winter

8. Based on the results of Study 1, which of the following can be concluded about the relationship between sodium (Na) concentration and the acidity of deposition?

F. The lower the concentration of Na, the more basic the precipitation.
G. The higher the concentration of Na, the more basic the precipitation.
H. The higher the concentration of Na, the more acidic the precipitation.
J. There is no correlation between the concentration of Na and acidity of the precipitation.

9. During which of the following months should there be the least concern for the health of frogs?

A. January
B. April
C. August
D. September

10. The precipitation collected in Study 1 is an example of which type of acid deposition?

F. Wet deposition
G. Dry deposition
H. Cloud deposition
J. Fog deposition

11. If the collection bucket used in Study 1 had been rinsed with sulfuric acid before collecting sample number 2, the resulting pH measurement would have been:

A. impossible to determine.
B. exactly 5.28.
C. lower than 5.28.
D. higher than 5.28.