ACT Practice Test Science Items

Based on Passage I, what conditions lead to the formation of metamorphic rocks?

• Temperature changes

• Pressure changes

• Chemical changes

• Weathering processes

According to Table 1, which facies corresponds to a high metamorphic grade?

• Facies C

• Facies G

• Facies D

• Facies B

• Facies A

What is the relationship between temperature and pressure in the formation of Facies C?

• Facies C forms at low temperature and low pressure.

• Facies C forms at high temperature and high pressure.

• Facies C forms at varying temperature and pressure conditions.

Which mineral is present in rocks of a high grade according to Figure 2?

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According to Figure 2, which of the following minerals would most typically be found only in rocks of a medium grade?

• Muscovite

• Biotite

• Kyanite

• Plagioclase

According to Figure 1, a Facies G rock will most likely form under which of the following pressure and temperature conditions?

• 3 kb 800°C

• 5 kb 400°C

• 8 kb 1,000°C

• 11 kb 600°C

Figure 1 indicates that as depth increases, pressure:

• decreases only

• remains the same

• increases only

• increases, then decreases

According to Figure 2, the presence of which of the following minerals in a metamorphic rock would be least helpful in determining that rock’s grade?

• Chlorite

• Muscovite

• Staurolite

• Plagioclase

Hornfels is a metamorphic rock formed when magma (molten rock) heats sedimentary rocks on Earth’s surface. According to Figure 1, hornfels is most likely a member of which of the following facies?

• Facies A

• Facies C

• Facies E

• Facies G

Which of the following phrases best describes the major point of difference between the 2 scientists’ hypotheses?

• The location of the event

• The speed the object was traveling

• The density of Earth’s atmosphere

• The type of object that entered Earth’s atmosphere