SOLUTION & EXPLANATION FOR TOEFL IBT READING PRACTICE TEST 05 ( FROM TOEFL IBT IVY’S READING 15 ACTUAL TESTS)
KEY
1. Vocabulary I (B)
Q. The word ascertain in the passage is closest in meaning to
Why? discover can replace ascertain in this context «■-See due 1(B)[lines 11-12]
• ascertain v. to learn something with certainty
• discover v. to find someone or something accidentally or with purpose
2. Sentence Simplification I (D)
Q. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
Why? Although radiocarbon dating cannot directly calculate the ages of inorganic materials, such as coins, // organic matter discovered on the same ground level, or stratum, can provide an accurate estimate based on the presumption that both objects once coexisted,
Why Not? (A) Minor
(B) Incorrect
(C) Information about the radiocarbon dating is left out.
3. Reference I (C)
Q. The word Its in the passage refers to
Why? Because of its broad applications, radiocarbon dating is utilized in various fields, such as archaeology, anthropology, and geology. **See Clue 3(C)[lines 19-22]
4. Factual Information I (A)
Q. Based on the information in paragraph 1 and paragraph 2, radiocarbon dating is used more often than other dating methods because it
Why? ~See Clue 4(A)[lines 5-7, 19-22]
Why Not? (B)-(D) Not supported
5. Factual Information I (C)
Q. According to paragraph 3, before radiocarbon dating scientists relied on the assumption that the artifacts that are the deepest underground
Why? See Clue 5(C)[lines 25-28]
Why Not? (A), (B), (D) Not mentioned
6. Vocabulary I (C)
Q. The word remnants in the passage is closest in meaning to
Why? remains can replace remnants in this context. It is inferred that the word artifacts in line 32 is close in meaning to remnants. ^See Clue 6(C)[lines 28-29, 31-32]
• remnant n. (pi.) small portion that remains after the rest of it has been used or destroyed
• remain n. (pi.) parts left after the rest has been destroyed or has disappeared
7. Factual Information | (A)
Q. According to paragraph 3, how (fid scientists determine the ages of archaeological samples before radiocarbon dating?
Why? ~See Clue 7(A)[lines 32-34]
► Accurately determining the age of a sample required confirmation from written records,…
Why Not? (B) Incorrect “-See lines 25-28/ (C), (D) Not mentioned
8. Factual Information I (D)
Q. According to paragraph 4, how did Libby’s technique benefit the field of archaeology?
Why? ~See Clue 8(D) lines 59-61]
► Libby found that by measuring the amount of ,4C that was left in organic material, the age of the subject could be estimated,… archaeological samples
Why Not? (A), (C) Not mentioned / (B) Incorrect—See lines 59-60
9. Inference I (A)
Q. What can be inferred from paragraph 4 about the rates of decay of some radioactive substances?
Why? (A) can be inferred from the information in lines 63-65. —See Clue 9(A)
Why Not? (B)-(D) Not supported
10. Factual Information I (B)
Q. According to paragraph 5, radiocarbon dating cannot accurately date samples older than fifty thousand years because
Why? -See Clue 10(B)[lines 78-80]
► In objects older than that the quantity of ™C is too small for scientists to examine and render a reliable conclusion.
Why Not? (A), (C), (D) Not mentioned
11. Rhetorical Purpose I (D)
Q. Why does the author mention the Dead Sea Scrolls in paragraph 5?
Why? The Dead Sea Scrolls are mentioned as objects for testing the effectiveness of the radiocarbon dating method. —See Clue 11(D)[lines 82-86]
12. Insert Text | [C]
Q. Look at the four squares [■] that indicate where the following sentence could be added to the passage.
Why? [B] Libby found that by measuring the amount of 14C that was left in organic material, the age of the subject could be estimated, as the rate of decay, or half-life of 14C, is gradual yet steady. [C] This slow rate of decay makes 14C ideal for use in determining the ages of ancient artifacts. Various radioactive substances have different rates of decay, ranging from seconds to thousands of years. [D]
► ‘This slow rate of decay” in the given sentence refers to “the rate of decay, or half-life of 14C, is gradual yet steady.”
13. Prose Summary
Q. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Why? The radiocarbon dating method is a procedure that measures the amount of 14C in organic remains and uses that information to accurately estimate the ages of old artifacts.
| Correct Answer Choices Clues in the passage | |
| (A) Because 14C is present in the atmosphere, it is constantly absorbed by living things and can be found in every organism. | Clue 13(A)[lines 44-46] When 14C, which is naturally present in very small quantities in the air, is absorbed by living organisms |
| (D) Although radiocarbon dating is limited to artifacts less than fifty thousand years old, it is a dependable and invaluable tool. | Clue 13(D)[lines 76-78] it can only estimate the ages of organic objects that are less than fifty thousand years old
[lines 81-82] the technique is still highly dependable [lines 91-92] radiocarbon dating is an invaluable tool |
| (E) Scientists have verified the preciseness of the radiocarbon dating method by testing it on artifacts whose ages are known. | Clue 13(E)[lines 83-85] the radiocarbon dating method has been tested on historically recorded artifacts whose ages are known [lines 87-90] the ages calculated by the radiocarbon dating technique closely match the ages of the artifacts as documented in historical records |
► The whole passage focuses on the principle and usefulness of radiocarbon dating. And it follows that ((A) The principle of radiocarbon dating — (D) Limitations of radiocarbon dating and its usefulness — (E) Test on the preciseness of radiocarbon dating)