TOEFL Reading Practice Test #41

Correct Answer: C. caught

Explanation:
In the passage, “trapped” is used in the context of oil being stuck or held in rock formations. “Caught” is the best synonym here because it implies being held or prevented from escaping, which fits the geological idea of oil being caught in a reservoir.

A. hidden – implies being deliberately concealed, but oil isn’t intentionally hidden.

B. destroyed – the opposite of what happens; the oil is preserved, not ruined.

D. found – refers to discovery, not the physical condition of being stuck or held.

Correct Answer: B. the chemical changes that occur in oil and natural gas after they have formed

Explanation:
The relevant section says:

"Two additional kinds of evidence support the hypothesis...: oil possesses optical properties... and oil contains nitrogen and certain compounds..."

It also mentions:

"Sampling... has shown that fine muds beneath the seafloor contain up to 8 percent organic matter."

A is correct — it refers to the mud under the seafloor with organic matter.

C is correct — optical properties of oil are cited as evidence.

D is correct — nitrogen and other compounds of biological origin are specifically mentioned.

B is incorrect because it talks about changes after oil and gas have formed. That section begins, “A complex sequence of chemical reactions is involved…” but those are about how oil forms or what happens after—not evidence for organic origin.

Correct Answer: C

Explanation:

C is accurate — it preserves both the cause (greater permeability) and the direction of movement (from shale to upper layers).

A distorts the cause-and-effect: permeability is not why they are squeezed out; it's why they migrate readily.

B misses the movement entirely and focuses only on storage.

D completely reverses the relationship by saying oil and gas are squeezed out of sandstones, which contradicts the passage.

Correct Answer: A

Explanation:
This sentence explains why oil doesn't stick to the rock as tightly as water does — because of weaker molecular attraction — which helps explain why oil moves through rock differently from water.

B is too specific — the passage doesn’t compare migration speeds between sandstone and limestone.

C is incorrect — the passage explicitly says oil and water do not mix.

D is off-topic — the sentence is about behavior, not molecular structure.

Correct Answer: D. appropriate

Explanation:
The passage says:

"Most of the petroleum that forms in sediments does not find a suitable trap..."
This means a trap that is appropriate for holding oil.

A. noticeable – unrelated to usefulness

B. permanent – not about time or durability

C. protected – doesn’t capture the idea of being effective for trapping

Correct Answer: C

Explanation:
The passage states:

"Most of the petroleum that forms in sediments does not find a suitable trap and eventually makes its way... to the surface of the sea."

A — most oil doesn't remain underground.

B — oil forms after burial, but this option confuses the process.

D — no mention of combining with minerals; only migration with groundwater.

Correct Answer: B

Explanation:
“Controversial” refers to disagreement. The context is the debate about how much oil exists globally, which implies conflicting expert opinions.

A – it may be important, but that’s not the meaning of controversial

C – longevity of the question isn’t the issue

D – the question isn’t broken into parts, it’s about differing views

Correct Answer: D

Explanation:
The text says:

"Knowing how much oil has been found in an intensively drilled area, such as eastern Texas..."

A — the oil in Texas has been pumped out.

B – the passage says estimates are made based on Texas, not that it was predicted.

C – the passage uses Texas as a known reference, not as a place of guessing.

Explanation:
The inserted sentence provides a logical inference from the previous one. Paragraph 2 first presents empirical data: high levels of organic matter in fine muds. The sentence you're inserting gives the scientific interpretation of that data: this is one reason scientists link petroleum to biological origins.

Then, the paragraph continues with additional supporting evidence: optical properties and nitrogen-based compounds. So the inserted sentence belongs after the mud evidence and before the discussion of additional evidence.

Why the other options are incorrect:
[■][1]: Before mentioning the muds, so there's no basis yet for “such muds.”

[■][3]: By this point, we’re already moving into the chemical transformation process, not the evidence for origin.

[■][4]: Too late; it would interrupt the flow of information and confuse the logical structure of the paragraph.

Correct Answers: A, C, F

Explanation:

A. Supported: The passage clearly explains how petroleum forms from organic matter under the seafloor.

C. Supported: The passage describes how some oil leaks away, but some becomes trapped in porous rock.

F. Supported: The final paragraph discusses the uncertainty in estimating how much oil remains and presents expert estimates.

Incorrect Options:

B. Not mentioned: There’s no discussion about organic matter needing to be evenly distributed or limited to 8%.

D. Slightly misleading: While the passage says 60% of oil is in rocks younger than 65 million years, not less than 2.5 million, so it’s factually off.

E. Incorrect reasoning: The passage says oil doesn’t bind tightly to quartz/carbonate, not that these rocks have strong attraction to oil.