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Quiz Chapter 6: Acid and Alkali

10 questions · Form 2 Science Bab 6: Acid and Alkali

10 questions · plays in fullscreen

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. What salt is produced when Nitric Acid neutralises Potassium Hydroxide?

  1. Potassium Chloride
  2. Potassium Nitrate
  3. Calcium Nitrate
  4. Potassium Sulphate
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Answer: B

Nitric Acid + Potassium Hydroxide → Potassium Nitrate + Water.

2. Which indicator turns RED in an acidic solution and YELLOW in an alkaline solution?

  1. Phenolphthalein
  2. Methyl Orange
  3. Litmus Paper
  4. Filter Paper
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Answer: B

Methyl Orange turns red in acidic conditions and yellow in neutral or alkaline conditions.

3. What is the defining characteristic of an alkali compared to other bases?

  1. It is insoluble in water
  2. It is a base that is soluble in water
  3. It reacts with metals to produce oxygen
  4. It has a pH value lower than 7
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Answer: B

An alkali is specifically defined as a water-soluble base that releases hydroxide ions (OH-) in water.

4. What products are formed during a complete neutralisation reaction between an acid and an alkali?

  1. Salt and Hydrogen gas
  2. Salt and Carbon dioxide
  3. Salt and Water
  4. Alkali and Oxygen gas
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Answer: C

Neutralisation is the reaction between an acid and a base/alkali that produces salt and water only.

5. Which pH value indicates a strong acid solution?

  1. pH 1
  2. pH 5
  3. pH 7
  4. pH 13
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Answer: A

The pH scale ranges from 0 to 14. A pH value closest to 0 (such as pH 1) represents a strong acid.

6. What happens when a piece of dry blue litmus paper is placed into dry citric acid crystals?

  1. It turns red immediately
  2. It turns white due to bleaching
  3. No color change occurs
  4. It turns green
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Answer: C

Acids require water to ionize and produce hydrogen ions; without water, dry acid crystals cannot exhibit acidic properties to turn dry blue litmus paper red.

7. What color does Universal Indicator show in a neutral solution such as pure distilled water (pH 7)?

  1. Red
  2. Green
  3. Purple
  4. Yellow
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Answer: B

Universal Indicator turns green at pH 7, indicating a neutral medium.

8. Why is toothpaste formulated to be mildly alkaline?

  1. To increase the production of bacteria in the mouth
  2. To neutralise organic acids produced by oral bacteria from food debris
  3. To react with enamel to generate hydrogen gas
  4. To lower the pH of saliva below 4
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Answer: B

Oral bacteria break down food remnants into acids that decay tooth enamel; mildly alkaline toothpaste neutralises these acids.

9. Which ion is produced by all acids when dissolved in water?

  1. Hydroxide ion (OH-)
  2. Hydrogen ion (H+)
  3. Chloride ion (Cl-)
  4. Sodium ion (Na+)
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Answer: B

Acids are substances that ionize in water to form hydrogen ions (H+), which are responsible for their acidic properties.

10. What is the expected color change of Phenolphthalein indicator when added to a solution of Sodium Hydroxide (alkali)?

  1. Turns Red
  2. Turns Pink
  3. Turns Yellow
  4. Remains Colorless
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Answer: B

Phenolphthalein is colorless in acidic and neutral solutions, but turns pink in alkaline solutions.

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