Home / iGCSE Chemistry (0620) Core:6.1 Physical and chemical changes: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core:6.1 Physical and chemical changes: Exam Style Questions Paper 1

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

Which process involves a chemical change?

A) adding sodium chloride to water
B) adding magnesium to hydrochloric acid
C) heating solid iodine until it turns into a gas
D) melting lead

▶️ Answer/Explanation
Solution

Ans: B

A chemical change involves the formation of new substances. Let’s analyze each option:

A) Dissolving NaCl in water is a physical change – the NaCl dissociates into ions but can be recovered by evaporation.

B) Magnesium reacting with hydrochloric acid produces magnesium chloride and hydrogen gas – a clear chemical change with new substances formed.

C) Iodine subliming is a physical change of state (solid to gas) with no new substances formed.

D) Melting lead is a physical change (change of state from solid to liquid).

Only option B represents a chemical change where new substances are formed.

Question

Which process is a chemical change?

A) boiling water
B) cooking an egg
C) dissolving sugar
D) melting ice cubes

▶️ Answer/Explanation
Solution

Ans: B

A chemical change results in the formation of new substances with different chemical properties. Cooking an egg involves the denaturation of proteins (irreversible change), which is a chemical change. Boiling water (A) and melting ice (D) are both physical changes as they only change the state of matter. Dissolving sugar (C) is also a physical change because the sugar molecules remain unchanged and can be recovered by evaporation.

Question

A sequence of changes involving sulfur is shown.

Which row describes the changes?

▶️Answer/Explanation

Ans:

C

The change from solid sulfur to liquid sulfur is a physical change, specifically a change of state or phase change. 

The change from liquid sulfur to sulfur dioxide gas (SO2) is a chemical change. During this process, the chemical composition of the substance changes as sulfur undergoes a chemical reaction to form sulfur dioxide.

Question

Which process involves a physical change?

A heating calcium carbonate

B burning wood

C melting an ice cube

D mixing an acid and a base

▶️Answer/Explanation

Ans:C

The melting of an ice cube represents a physical change, specifically a phase change, as it involves the transformation of a solid (ice) into a liquid (water) without any alteration in chemical composition.

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