An actual ACT Science Test contains 40 questions to be answered in 40 minutes. This quiz contains REAL QUESTIONS from the ACT to help you sharpen your skills.
Directions
The passage in this test is followed by several questions. After reading the passage, choose the best answer to each question and fill in the corresponding oval on your answer screen. You may refer to the passage as often as necessary. Access to your answer key will be provided at the end of the quiz.
You are not permitted to use a calculator on this test...but remember, this is practice for you!
Passage
The coastline of Antarctica consists of many ice shelves (floating 100–1,000100 through 1,000 m thick sheets of ice that extend from a landmass). Many of these ice shelves are melting, causing them to calve (break off) large pieces known as icebergs. Four students each explain iceberg calving.
Student 1
Antarctic ice shelves melt due to the warming of the air above the surface of the ice during the summer. When the air temperature increases, the surface ice melts and water pools. The meltwater moves downward into the ice shelf, causing fractures to form. The accumulation of many fractures in the ice over many summers gradually leads to icebergs calving from an ice shelf.
Student 2
Student 1 is correct that an increase in air temperature during the summer leads to surface ice melting and water pooling, causing fractures to form in the ice. However, the action of the meltwater alone is insufficient to produce fractures deep enough to cause calving. When the air temperature lowers at the beginning of winter, falling snow accumulates in the fractures, increasing the pressure on the ice, eventually causing calving. After a large snowfall, calving can occur within a few days.
Student 3
Antarctic ice shelves melt only from below. During the summer, ocean currents circulate water that is just above freezing into and out of the basal cavity (the area underneath an ice shelf), causing the ice within the cavity to melt. For every 0.1°degreeC that the ocean water is above freezing, the water melts a thickness of 10 m of ice from the bottom per year. When the ice shelf thickness has been reduced by at least 50 m, calving occurs.
Student 4
The warmer water circulated by ocean currents melts the ice shelf as described by Student 3. However, calving cannot occur from this process alone. Snow accumulates on the surface of the ice each winter, but each following summer, warm air leads to the melting and compaction of the snow. The compaction lowers the surface of the ice shelf, pushing the ice down into the basal cavity, where it is melted by the ocean water. After several winter-summer cycles, the ice shelf becomes top-heavy due to the snow and the melting from below, and calving occurs.
Question 1 of 6
Which of the following diagrams best shows the location of the basal cavity as described by Student 3?
Question 2 of 6
Suppose that the air temperature along the Antarctic coastline is never warmer than –negative 10° degrees C and that the atmospheric pressure is always 1.0 atmosphere. Does this information support the description given by Student 1?
Question 3 of 6
Based on the description of the icebergs that are calved along the coastline of Antarctica, do the icebergs sink or float?
Question 4 of 6
Which of Students 1 and 4, if either, implied that the processes involved in iceberg calving will take more than one year to result in the formation of an iceberg?
Question 5 of 6
In regard to the season(s) involved in iceberg calving, how does Student 2’s description differ from Student 3’s description? Student 2 indicated that:
Question 6 of 6
Which of Students 2, 3, and 4 agree(s) with Student 1 that some form of melting occurs on the ice shelf surface?
Please select an answer
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