CIE iGCSE Co-Ordinated Science C6.1 Physical and chemical changes Exam Style Questions Paper 2
▶️ Answer/Explanation
Heating zinc carbonate produces zinc oxide (a new solid) and carbon dioxide gas: \(ZnCO_3 \rightarrow ZnO + CO_2\).
Since new substances with different properties are formed, this is thermal decomposition, a chemical change (and it absorbs energy, so it is not exothermic).
✅ Answer: (A)
Since new substances with different properties are formed, this is thermal decomposition, a chemical change (and it absorbs energy, so it is not exothermic).
✅ Answer: (A)
▶️ Answer/Explanation
Heating ice to form water is a change of state, which is reversible and involves no new substance, so it is physical.
Lighting a match is a combustion reaction that produces new substances such as carbon dioxide and water, so it is a chemical change.
Removing zinc from sodium chloride solution by filtration only physically separates an insoluble solid from a solution without forming new substances, so it is physical.
✅ Answer: (C)
Lighting a match is a combustion reaction that produces new substances such as carbon dioxide and water, so it is a chemical change.
Removing zinc from sodium chloride solution by filtration only physically separates an insoluble solid from a solution without forming new substances, so it is physical.
✅ Answer: (C)
▶️ Answer/Explanation
Boiling, dissolving and melting are physical changes because no new substance is formed and the change is generally reversible.
Neutralisation involves an acid reacting with a base to form new substances: a salt and water.
Since new chemical substances are produced, this is a chemical change.
✅ Answer: (D)
Neutralisation involves an acid reacting with a base to form new substances: a salt and water.
Since new chemical substances are produced, this is a chemical change.
✅ Answer: (D)
Question
Which changes are chemical changes?
1. iron rusting
2. burning coal
3. dissolving sugar in water
4. boiling water
(A) 1 and 2 (B) 1 and 3 (C) 2 and 4 (D) 3 and 4
▶Answer/Explanation
Ans :A
Question
When solid zinc carbonate is heated, a different solid and a gas are formed.
Which type of change occurs?
A chemical
B exothermic
C physical
D separation
▶️Answer/Explanation
Ans : A