How Soap Cleans: Reading Answers & Explanations
IELTS Reading practice test · 14 questionsAcademicmedium
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About this passage
The passage opens: “Water is often described as a universal solvent, but anyone who has tried to wash greasy hands under a running tap knows that this description has its limits. Water readily dissolves salt and sugar, yet it slides straight off oil and fat without lifting them away.”
- Passage length: about 769 words
- Questions: 14
- Question types: True / False / Not Given, Multiple Choice, Short Answer
“How Soap Cleans” 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
How Soap Cleans 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
Water easily dissolves oils and fats on its own.
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Answer: FALSE
Why: This sentence directly contradicts the statement, so the answer is FALSE.
Evidence · Paragraph 1 “…it slides straight off oil and fat without lifting them away.”
- 2
A soap molecule has one end attracted to water and another attracted to grease.
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Answer: TRUE
Why: This sentence confirms the statement, so the answer is TRUE.
Evidence · Paragraph 2 “A single molecule, in other words, is friendly to water at one end and friendly to grease at the other.”
- 3
The tiny spheres that trap oil inside them are called micelles.
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Answer: TRUE
Why: This sentence confirms the statement, so the answer is TRUE.
Evidence · Paragraph 3 “These little spheres are known as micelles.”
- 4
Soap increases the surface tension of water.
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Answer: FALSE
Why: This sentence directly contradicts the statement, so the answer is FALSE.
Evidence · Paragraph 4 “Soap weakens these attractions between water molecules, lowering the surface tension”
- 5
Synthetic detergents do not form scum in hard water.
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Answer: TRUE
Why: This sentence confirms the statement, so the answer is TRUE.
Evidence · Paragraph 6 “…chemists have developed synthetic surfactants, often called detergents, which are built to do the same job as soap but do not form scum in hard water.”
- 6
Liquid detergents clean clothes faster than bars of soap.
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Answer: NOT GIVEN
Why: The statement claims liquid detergents clean clothes faster than bars of soap, but the passage never confirms or denies this, only explaining how soap works and mentioning its reaction with hard water.
Closest related text · Paragraph 7 “Whether the cleaning agent is an ancient bar of soap or a modern liquid detergent, the underlying principle is the same.”
Question 7: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. Because water is charged while oils are non-polar
- B. Because oil is heavier than water
- C. Because oil evaporates too quickly
- D. Because water is too cold
- 7
Why do water and oil refuse to mix?
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Answer: A — Because water is charged while oils are non-polar
Why: This is the part of the passage that supports A — Because water is charged while oils are non-polar.
Evidence · Paragraph 1 “Oils and fats, by contrast, carry no such charges. They are described as non-polar, and because water and oil have such different characters they refuse to mix.”
Question 8: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. They point outward into the water
- B. They bury themselves in the droplets of oil
- C. They dissolve in the water
- D. They react with the grease to form scum
- 8
What happens to the water-fearing tails of soap molecules around greasy dirt?
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Answer: B — They bury themselves in the droplets of oil
Why: This is the part of the passage that supports B — They bury themselves in the droplets of oil.
Evidence · Paragraph 3 “The water-fearing tails bury themselves in the droplets of oil, while the water-loving heads remain pointing outward into the surrounding water.”
Question 9: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. It makes the water hotter
- B. It removes the minerals from hard water
- C. It allows water to spread and soak into materials more easily
- D. It makes the soap dissolve faster
- 9
How does lowering surface tension help cleaning?
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Answer: C — It allows water to spread and soak into materials more easily
Why: This is the part of the passage that supports C — It allows water to spread and soak into materials more easily.
Evidence · Paragraph 4 “…lowering the surface tension so that the water spreads out and soaks into materials far more easily.”
Question 10: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. The formation of scum in hard water
- B. The lowering of surface tension by detergents
- C. The trapping of oil inside a micelle
- D. The reaction of heating fats or oils with a strong alkali
- 10
What is saponification?
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Answer: D — The reaction of heating fats or oils with a strong alkali
Why: This is the part of the passage that supports D — The reaction of heating fats or oils with a strong alkali.
Evidence · Paragraph 5 “…heating fats or oils together with a strong alkali, in a reaction known as saponification.”
Questions 11–14: Short Answer
Answer the questions below. Choose NO MORE THAN THREE WORDS from the passage for each answer.
- 11
What is the general family name for substances such as soap?(max 2 words)
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Answer: surfactants (also accepted: surfactant)
Why: The answer “surfactants” is taken from this sentence — copy the word(s) exactly as they appear. It fits the 2-word limit.
Evidence · Paragraph 2 “Soap belongs to a family of substances that chemists call surfactants”
- 12
What word describes the water-loving end of a soap molecule?(max 2 words)
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Answer: hydrophilic
Why: The answer “hydrophilic” is taken from this sentence — copy the word(s) exactly as they appear. It fits the 2-word limit.
Evidence · Paragraph 2 “One end is attracted to water and is described as hydrophilic, meaning water-loving.”
- 13
What effect makes the surface of water behave like a taut skin?(max 3 words)
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Answer: surface tension
Why: The answer “surface tension” is taken from this sentence — copy the word(s) exactly as they appear. It fits the 3-word limit.
Evidence · Paragraph 4 “…an effect known as surface tension that is caused by water molecules pulling strongly on one another.”
- 14
Which two dissolved metals in hard water react with soap to form scum?(max 3 words)
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Answer: calcium and magnesium (also accepted: calcium, magnesium)
Why: The answer “calcium and magnesium” is taken from this sentence — copy the word(s) exactly as they appear. It fits the 3-word limit.
Evidence · Paragraph 6 “…particularly compounds of calcium and magnesium.”
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 “How Soap Cleans” under exam conditions
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