Why the Sky Is Blue: Reading Answers & Explanations
IELTS Reading practice test · 14 questionsAcademicmedium
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About this passage
The passage opens: “On a clear day the sky overhead is a deep and even blue, a colour so familiar that few people stop to ask where it comes from. The answer is not obvious, because the air itself is colourless and the sunlight that fills it appears white.”
- Passage length: about 767 words
- Questions: 14
- Question types: True / False / Not Given, Multiple Choice, Short Answer
“Why the Sky Is Blue” is an original IELTS-style practice passage written by IELTS-Bank. It is not taken from an official IELTS or Cambridge test, so these answers only apply to our version.
Answer key at a glance
Why the Sky Is Blue answers with explanations
Questions 1–6: True / False / Not Given
Do the following statements agree with the information given in the passage? Write TRUE if the statement agrees, FALSE if it contradicts, or NOT GIVEN if there is no information.
- 1
Sunlight is made up of a mixture of all the colours of the rainbow.
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Answer: TRUE
Why: This sentence confirms the statement, so the answer is TRUE.
Evidence · Paragraph 2 “Although sunlight looks white, it is in fact a mixture of all the colours of the rainbow.”
- 2
Red light has a shorter wavelength than blue light.
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Answer: FALSE
Why: This sentence directly contradicts the statement, so the answer is FALSE.
Evidence · Paragraph 2 “Red light has the longest waves, while blue and violet light have the shortest.”
- 3
Short wavelengths of light are scattered more strongly than long ones.
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Answer: TRUE
Why: This sentence confirms the statement, so the answer is TRUE.
Evidence · Paragraph 3 “Short waves are scattered far more powerfully than long ones, so the blue part of sunlight is thrown about the sky many times more than the red part.”
- 4
The human eye is more sensitive to violet light than to blue light.
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Answer: FALSE
Why: This sentence directly contradicts the statement, so the answer is FALSE.
Evidence · Paragraph 5 “…the human eye is far less sensitive to violet than to blue.”
- 5
Rainbows are formed by the same scattering process that colours the sky.
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Answer: NOT GIVEN
Why: The statement claims that rainbows are formed by the same scattering process as the sky's color, but the passage never confirms or denies this, only explaining how scattering affects the sky's color.
- 6
On the Moon the sky appears black even in sunlight.
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Answer: TRUE
Why: This sentence confirms the statement, so the answer is TRUE.
Evidence · Paragraph 7 “An astronaut standing on the airless Moon sees a black sky even in full sunlight, because there are no molecules to scatter the Sun's rays”
Question 7: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. It is absorbed completely by the molecules
- B. It is sent off in new directions in a process called scattering
- C. It is turned into heat
- D. It passes through unchanged
- 7
What happens when light strikes the gas molecules in the atmosphere?
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Answer: B — It is sent off in new directions in a process called scattering
Why: This is the part of the passage that supports B — It is sent off in new directions in a process called scattering.
Evidence · Paragraph 3 “…when light strikes them it is sent off in new directions in a process known as scattering.”
Question 8: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. Because the Sun is blue
- B. Because blue light is scattered in every direction by the air
- C. Because the air is coloured blue
- D. Because red light is scattered towards us
- 8
Why do we see blue light coming from all parts of the sky?
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Answer: B — Because blue light is scattered in every direction by the air
Why: This is the part of the passage that supports B — Because blue light is scattered in every direction by the air.
Evidence · Paragraph 4 “Because blue light is scattered in every direction by the air, it reaches our eyes from all parts of the sky rather than only from the direction of the Sun.”
Question 9: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. Because the Sun produces only red light in the evening
- B. Because the atmosphere becomes thinner at sunset
- C. Because the blue light is scattered away over the longer path, leaving mainly reds
- D. Because the eye stops detecting blue at night
- 9
Why does the setting Sun appear red?
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Answer: C — Because the blue light is scattered away over the longer path, leaving mainly reds
Why: This is the part of the passage that supports C — Because the blue light is scattered away over the longer path, leaving mainly reds.
Evidence · Paragraph 6 “…almost all of the blue light is scattered away sideways and lost, leaving mainly the reds and oranges to travel straight through to our eyes.”
Question 10: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. a property of light alone
- B. a property of the air alone
- C. the meeting between light and air
- D. the temperature of the atmosphere
- 10
According to the passage, the colour of the sky is best described as a result of
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Answer: C — the meeting between light and air
Why: This is the part of the passage that supports C — the meeting between light and air.
Evidence · Paragraph 7 “The colour of the sky is thus not a property of light or of air by itself, but of the meeting between the two.”
Questions 11–14: Short Answer
Answer the questions below. Choose NO MORE THAN THREE WORDS from the passage for each answer.
- 11
What piece of glass spreads a beam of sunlight into a band of colours?(max 3 words)
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Answer: a glass prism (also accepted: glass prism / a prism / prism)
Why: The answer “a glass prism” is taken from this sentence — copy the word(s) exactly as they appear. It fits the 3-word limit.
Evidence · Paragraph 2 “When a beam of sunlight passes through a glass prism, it spreads out into a band of colours”
- 12
What are the two main gases in the atmosphere that light meets?(max 3 words)
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Answer: nitrogen and oxygen (also accepted: nitrogen, oxygen)
Why: The answer “nitrogen and oxygen” is taken from this sentence — copy the word(s) exactly as they appear. It fits the 3-word limit.
Evidence · Paragraph 3 “…it meets countless molecules of gas, chiefly nitrogen and oxygen.”
- 13
What is the process called in which light is sent off in new directions by molecules?(max 2 words)
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Answer: scattering
Why: The answer “scattering” is taken from this sentence — copy the word(s) exactly as they appear. It fits the 2-word limit.
Evidence · Paragraph 3 “…it is sent off in new directions in a process known as scattering.”
- 14
What does the passage say remains visible during the day on the Moon?(max 2 words)
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Answer: the stars (also accepted: stars)
Why: The answer “the stars” is taken from this sentence — copy the word(s) exactly as they appear. It fits the 2-word limit.
Evidence · Paragraph 7 “…and the stars remain visible in daytime.”
Estimated band score for this test
Your raw score out of 14 scaled to the 40-question IELTS Reading (Academic) conversion table. This is the same estimate the practice page shows after you submit. A single passage is a small sample, so treat it as a guide.
| Correct answers | Estimated band |
|---|---|
| 14 / 14 | 9.0 |
| 13 / 14 | 8.5 |
| 12 / 14 | 7.5 |
| 11 / 14 | 7.0 |
| 10 / 14 | 6.5 |
| 8–9 / 14 | 6.0 |
| 7 / 14 | 5.5 |
| 6 / 14 | 5.0 |
| 5 / 14 | 4.5 |
| 4 / 14 | 4.0 |
| 3 / 14 | 3.5 |
| 2 / 14 | 3.0 |
| 1 / 14 | 2.0 |
| 0 / 14 | 0.0 |
Full-test score? Use the IELTS band calculator.
Tips for the question types in this test
True / False / Not Given
- Read the statement first and underline the key idea, especially any qualifiers like "all", "only", "never", "always", "more than" or dates and numbers.
- Because the questions follow the order of the passage, scan for the paragraph that deals with the same topic rather than re-reading everything.
Common trap: Confusing "False" with "Not Given": choose False only when the passage actively contradicts the statement; if the passage is silent, it is Not Given.
Full True / False / Not Given strategyMultiple Choice
- Read the question stem carefully before the options so you know exactly what is being asked.
- Because multiple-choice questions follow passage order, locate the relevant section and read it in full — the answer usually depends on more than one sentence.
Common trap: Distractors that use exact words from the passage but distort the meaning.
Full Multiple Choice strategyShort Answer
- Read the instructions and note the exact word limit; going over it means zero marks even if the meaning is right.
- Turn each question into a set of keywords and predict what kind of answer it needs (a person, a date, a place, a noun).
Common trap: Exceeding the word limit (writing four words when only three are allowed).
Full Short Answer strategyPractise “Why the Sky Is Blue” under exam conditions
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