CIE iGCSE Co-Ordinated Science C7.1 The characteristic properties of acids and bases Exam Style Questions Paper 2
▶️ Answer/Explanation
The reaction between an acid and an alkali is a neutralisation reaction. In this reaction, the acid neutralises the alkali to produce a salt and water. Therefore, X represents the salt formed. The specific salt produced depends on the particular acid and alkali used in the reaction. Option A is incorrect because the alkali itself is a base, and the acid is already a reactant.
✅ Answer: (D)
✅ Answer: (D)
▶️ Answer/Explanation
The pH of the indicator solution decreasing shows that carbon dioxide gas is being produced and dissolving in it, forming carbonic acid.
Only a reaction between hydrochloric acid and a carbonate releases \(CO_2\) gas as a product.
Zinc carbonate is the solid that reacts with the acid to release \(CO_2\).
✅ Answer: (B)
Only a reaction between hydrochloric acid and a carbonate releases \(CO_2\) gas as a product.
Zinc carbonate is the solid that reacts with the acid to release \(CO_2\).
✅ Answer: (B)
▶️ Answer/Explanation
Neutralisation follows \(H^+ + OH^- \rightarrow H_2O\), confirming statement \(1\).
A neutral solution has \(pH = 7\), which turns universal indicator green, confirming statement \(3\); statements \(2\) and \(4\) wrongly reverse the direction of ion/proton transfer.
✅ Answer: (A)
A neutral solution has \(pH = 7\), which turns universal indicator green, confirming statement \(3\); statements \(2\) and \(4\) wrongly reverse the direction of ion/proton transfer.
✅ Answer: (A)
▶️ Answer/Explanation
Limestone, calcium carbonate, is a base that neutralises excess acidity commonly found in soil.
Neutralising acid raises the pH of the soil towards neutral, making it more suitable for growing crops.
Limestone contains no nitrogen and does not directly supply plant nutrients, so it does not act as a fertiliser.
✅ Answer: (D)
Neutralising acid raises the pH of the soil towards neutral, making it more suitable for growing crops.
Limestone contains no nitrogen and does not directly supply plant nutrients, so it does not act as a fertiliser.
✅ Answer: (D)
▶️ Answer/Explanation
Chlorine gas dissolves in the moisture on damp litmus paper and acts as a bleaching agent.
This bleaching action turns the damp red litmus white, rather than simply changing its colour due to acidity.
\(CO_2\) and \(SO_2\) are acidic gases but only turn blue litmus red, not red litmus, and \(H_2\) has no effect on litmus.
✅ Answer: (B)
This bleaching action turns the damp red litmus white, rather than simply changing its colour due to acidity.
\(CO_2\) and \(SO_2\) are acidic gases but only turn blue litmus red, not red litmus, and \(H_2\) has no effect on litmus.
✅ Answer: (B)