CIE iGCSE Co-Ordinated Science C7.1 The characteristic properties of acids and bases Exam Style Questions Paper 1
Question
What reacts with ammonia gas?
| Option | Hydrochloric Acid | Sodium Hydroxide |
|---|---|---|
| A | ✓ | ✓ |
| B | ✓ | ✗ |
| C | ✗ | ✓ |
| D | ✗ | ✗ |
▶️Answer/Explanation
Answer: B
Explanation: Ammonia gas reacts with hydrochloric acid to form ammonium chloride, but it does not react with sodium hydroxide.
Question
A gas turns damp litmus paper white. What is the gas?
A. carbon dioxide
B. chlorine
C. hydrogen chloride
D. sulfur dioxide
▶️Answer/Explanation
Answer: B. chlorine
Explanation: Chlorine gas (Cl₂) bleaches damp litmus paper, turning it white. Carbon dioxide, hydrogen chloride, and sulfur dioxide do not have this effect.
Question
Calcium carbonate (limestone) is a base. Which uses of limestone depend on it acting as a base?
1 making lime
2 neutralising acid waste
3 stone buildings
4 treatment of soil
A 1 and 2
B 2 and 3
C 2 and 4
D 3 and 4
▶️Answer/Explanation
Answer: C 2 and 4
Explanation: Limestone is used to neutralize acid waste and to treat acidic soils because it is a base. Making lime and using it in stone buildings do not depend on its basic properties.
Question
The colour of universal indicator in solutions S, T and U is shown.
Which row shows the pH values of the solutions?
A S: 1 / T: 5 / U: 9
B S: 1 / T: 7 / U: 14
C S: 4 / T: 5 / U: 9
D S: 4 / T: 7 / U: 14
▶Answer/Explanation
Answer: D
Explanation: Universal indicator turns orange at pH 4 (acidic), green at pH 7 (neutral), and purple at pH 14 (strongly alkaline).
Question
Which substances neutralise acids?
1 lime
2 limestone
3 calcium hydroxide
A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3
▶️Answer/Explanation
Ans :B
Question
When aqueous potassium hydroxide is warmed with ammonium chloride, a gas is given off.
Which test result identifies the gas?
A It bleaches pH paper.
B It turns anhydrous cobalt(II) chloride blue.
C It turns universal indicator red.
D It turns red litmus blue.
▶️Answer/Explanation
Ans :A
Question
A metal oxide powder is added to a dilute acid.
The initial temperature of the acid is 21 ºC. The pH of the acid is 2.
When all the acid has reacted, the temperature of the reaction mixture is 23 ºC and the pH is 7.
Which statement describes this reaction?
(A) It is endothermic and neutralisation.
(B) It is endothermic and oxidation.
(C) It is exothermic and neutralisation
(D) It is exothermic and oxidation.
▶️Answer/Explanation
Ans: C
Question
Indigestion is caused by excess hydrochloric acid in the stomach.
Which substance can be used to neutralise the acid?
▶️Answer/Explanation
Ans: D
Question
Copper carbonate is reacted with dilute hydrochloric acid.
Which gas is given off?
(A) carbon dioxide
(B) hydrogen
(C) nitrogen
(D) sulfur dioxide
▶️Answer/Explanation
Ans : A
Question
Potassium oxide and sulfur dioxide are both soluble in water.
Which row describes properties of these oxides?
▶️Answer/Explanation
Ans : A
Question
Element X burns in air to produce an oxide.
A solution of the oxide has a pH value of 10.
What is X?
(A) argon
(B) carbon
(C) magnesium
(D) phosphorus
▶️Answer/Explanation
Ans: C
Question
What reacts with ammonia gas?
▶Answer/Explanation
Ans : B
Question
A label from a packet of indigestion tablets is shown.
Which substance does not neutralise stomach acid?
A. magnesium carbonate
B. magnesium hydroxide
C. magnesium oxide
D. magnesium sulfate
▶️Answer/Explanation
Answer: D. magnesium sulfate
Explanation: Magnesium sulfate does not neutralise stomach acid because it is a salt and does not react with acids. The other substances (magnesium carbonate, magnesium hydroxide, and magnesium oxide) are bases that can neutralise stomach acid.
Question
Which compound is prepared by reacting an acid with a base?
A) calcium oxide
B) copper hydroxide
C) hydrogen chloride
D) magnesium sulfate
▶️Answer/Explanation
Answer: D) magnesium sulfate
Explanation: Magnesium sulfate is formed by the reaction of sulfuric acid (acid) with magnesium hydroxide (base). This is an example of a neutralization reaction.
Question
Some soil is treated with limestone to make it neutral. What is the pH of the soil before it is treated?
A) 5
B) 7
C) 9
D) 11
▶️Answer/Explanation
Answer: A) 5
Explanation: Limestone (calcium carbonate) is used to neutralize acidic soils. Therefore, the soil must have been acidic (pH less than 7) before treatment. A pH of 5 is acidic.
Question
Which gas turns damp red litmus paper blue?
A. ammonia
B. carbon dioxide
C. chlorine
D. hydrogen
▶️Answer/Explanation
Answer: A. ammonia
Explanation: Ammonia is an alkaline gas, and it turns damp red litmus paper blue. Carbon dioxide and chlorine are acidic gases, while hydrogen is neutral.
Question
An acid neutralises solution X. A neutral solution is formed. What are the pH values of solution X and of the neutral solution?
| pH of solution X | pH of neutral solution | |
|---|---|---|
| A | 2 | 7 |
| B | 2 | 12 |
| C | 12 | 2 |
| D | 12 | 7 |
▶️Answer/Explanation
Answer: D
Explanation: A neutral solution has a pH of 7. If an acid neutralises solution X, then solution X must be basic (pH > 7). Therefore, the pH of solution X is 12, and the pH of the neutral solution is 7.
Question
The pH values of four liquids are 1, 4, 7 and 13. The four liquids are distilled water, nitric acid, potassium hydroxide and vinegar.
Which row shows the pH values of the liquids?
| distilled water | nitric acid | potassium hydroxide | vinegar | |
|---|---|---|---|---|
| A | 4 | 7 | 13 | 1 |
| B | 4 | 13 | 7 | 1 |
| C | 7 | 1 | 4 | 13 |
| D | 7 | 1 | 13 | 4 |
▶️Answer/Explanation
Answer: D. 7, 1, 13, 4
Explanation: Distilled water is neutral (pH 7), nitric acid is strongly acidic (pH 1), potassium hydroxide is strongly alkaline (pH 13), and vinegar is weakly acidic (pH 4).
Question
Which substances neutralise acids?
1. lime
2. limestone
3. calcium hydroxide
A. 1 and 2 only
B. 1 and 3 only
C. 2 and 3 only
D. 1, 2 and 3
▶️Answer/Explanation
Answer: D. 1, 2 and 3
Explanation: Lime (calcium oxide), limestone (calcium carbonate), and calcium hydroxide are all bases that can neutralize acids by reacting with them to form salts and water.
Question
Which row identifies the types of oxides?
▶️Answer/Explanation
Answer: D
Explanation: Acidic oxides, such as CO2 and SO2, react with bases to form salts. Basic oxides, such as CaO and Na2O, react with acids to form salts.