PETERSON TOEFL PBT PRACTICE TEST 2 PART 6

For centuries, sky watchers have reported seeing mysterious flashes of light on he surface of the Moon. Modern astronomers have observed the same phenomenon, but no one has been able to satisfactorily explain how or why the Moon sporadically sparks. However, researchers now believe they have found the cause.

Researchers have examined the chemical content of Moon rocks retrieved by astronauts during the Apollo missions and have found that they contain volatile gases such as helium, hydrogen, and argon. The researchers suggest that stray electrons, freed when the rock cracks, may ignite these gases. Indeed, lunar rock samples, when fractured in the lab, throw off sparks.

What causes these rocks to crack on the lunar surface? The flashes are most often seen at the borders between sunlight and shade on the Moon, where the surface is being either intensely heated or called. A sudden change in temperature may cause thermal cracking. Another possibility is change in temperature may cause thermal cracking. Another possibility is that meteors may strike the rocks and cause them to crack. Finally, lunar rocks may be fractured by seismic events – in other words, by tiny moon quakes.

1.         Which of the following statements describes the organization of the passage?

A.       A popular notion is refuted.

B.       A generalization is made, and examples of it are given.

C.       The significance of an experiment is explained.

D.       The phenomenon is described, and a possible explanation is proposed.

2.         According to the passage, how long have people been aware of the mysterious lights on the moon?

A.       For the last ten years

B.       Since the Apollo moon missions

C.       For hundreds of years

D.       For thousand of years

3.         The word sporadically (line 3) is closest in meaning to which of the following?

A.       Reputedly

B.       Occasionally

C.       Mysteriously

D.       Constantly

4.         According to the passage, the theory that Moon rocks give off sparks when they crack is supported by

A.       a telescopic study of the moon

B.       experiments conducted by astronauts

C.       observations made centuries ago

D.       an analysis of rocks from the Moon

5.         In line 6, the word they refers to

A.       helium, hydrogen, and argon

B.       researchers

C.       Apollo spacecraft

D.       lunar rocks

6.         The word stray in line 7 is closest in meaning to which of the following?

A.       Loose

B.       Speeding

C.       Fiery

D.       Spinning

7.         Which of the following situations is an example of ‘thermal cracking’ as described in the passage?

A.       A dam breaks when water rises behind it.

B.       A stone cracks open because of the pressure of tree roots.

C.       A cool glass breaks when it is filled with boiling water.

D.       An ice cube melts in the heat of the sun.

8.         All of the following are given as reasons for Moon rocks cracking EXCEPT

A.       seismic actions

B.       sudden temperature changes

C.       the action of meteors

D.       the pressure of gases

ANSWER KEY

1.             D

2.             C

3.             B

4.             D

5.             D

6.             A

7.             C

8.             D