Home / iGCSE Chemistry (0620) Core:11.7 Carboxylic acids: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core:11.7 Carboxylic acids: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core Paper 1 - All Chapters
Question

Which statements about dilute ethanoic acid are correct?

  1. It has a pH of 8.
  2. It is an organic compound.
  3. It turns universal indicator orange-yellow.
  4. It reacts with magnesium to produce carbon dioxide.

A) 1 and 3
B) 1 and 4
C) 2 and 3
D) 2 and 4

▶️ Answer/Explanation
Solution

Ans: C

Evaluating each statement about ethanoic acid (CH3COOH):

1. False: Acids have pH < 7. pH 8 would be alkaline.

2. True: Ethanoic acid contains carbon and is an organic compound.

3. True: As a weak acid, it turns universal indicator orange-yellow (pH ~3-6).

4. False: It reacts with magnesium to produce hydrogen gas, not CO2.

Therefore, only statements 2 and 3 are correct, making option C the right answer.

Question

What are the properties of aqueous ethanoic acid?

 decolourises aqueous brominereacts with calcium carbonate to make carbon dioxideturns damp red litmus paper blue
A✓✓✗
B✓✗✓
C✗✓✗
D✗✗✓
▶️ Answer/Explanation
Solution

Ans: C

Let’s analyze each property of aqueous ethanoic acid:

1. Decolourises aqueous bromine: Ethanoic acid does not decolourise bromine water as it doesn’t have any double bonds (unlike unsaturated compounds). So this should be ✗.

2. Reacts with calcium carbonate: Ethanoic acid is a weak acid but will react with calcium carbonate to produce carbon dioxide gas. This is ✓.

3. Turns damp red litmus blue: Acids turn blue litmus red, not the other way around. So this should be ✗.

Only option C matches all these observations (✗, ✓, ✗).

Question

Ethanoic acid reacts with aqueous sodium carbonate.

Which gas is given off in this reaction?

A) hydrogen
B) carbon dioxide
C) carbon monoxide
D) oxygen

▶️ Answer/Explanation
Solution

Ans: B

When ethanoic acid (a weak acid) reacts with sodium carbonate (a base), a neutralization reaction occurs producing sodium ethanoate, water, and carbon dioxide gas. The reaction can be represented as: \( 2CH_3COOH + Na_2CO_3 \rightarrow 2CH_3COONa + H_2O + CO_2 \). This is a standard test for carboxylic acids – they produce effervescence (bubbles) of carbon dioxide when reacted with carbonates. The other gases listed are not products of this reaction.

Question

 Some properties of an organic compound $\mathrm{J}$ are listed.

  • It is a liquid at room temperature.
  • It is soluble in water.
  • A solution of $\mathrm{J}$ reacts with calcium carbonate to form carbon dioxide.
  • A solution of $\mathrm{J}$ has a $\mathrm{pH}$ of 3 .

In which homologous series does $\mathrm{J}$ belong?

A alkane

B alkene

C alcohol

D carboxylic acid

▶️Answer/Explanation

Ans:D

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