States of Matter and Diffusion: Question 6
Syllabus 1.1
A jeweller heats a small blob of solid gold in a crucible with a blowtorch until it turns into a shiny, flowing liquid, ready to be poured into a mould. Just before pouring, the jeweller examines the liquid gold inside the crucible.
Which statement correctly describes the particle separation, arrangement and motion of the liquid gold at this moment?
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Worked solution
Step 1: Identify the state being described
The gold has just been heated until it “turns into a shiny, flowing liquid”, so at the moment described, the gold is a liquid, not a solid or a gas.
Step 2: Recall how particles behave in each state
- Solid: particles close together, regular arrangement, vibrating about fixed positions only.
- Liquid: particles close together (touching), random arrangement, able to move and slide past one another.
- Gas: particles far apart, random arrangement, moving quickly in random directions.
Step 3: Match the description to a liquid
Liquid gold’s particles are still close together, a liquid does not expand to fill a container the way a gas does, but, unlike in a solid, they are no longer held in a fixed arrangement. This is why liquid gold can flow and be poured: its particles are free to move and slide past each other while remaining in contact.
This matches option C.
Why the other options are wrong
- A: describes a gas, particles far apart, not close together as in a liquid.
- B: describes a solid. Particles vibrating in fixed positions, unable to move from place to place, which would not allow the gold to flow.
- D: mixes properties that do not belong together, gas-like separation with solid-like fixed vibration, and does not describe any real state of matter.
Final answer
- Liquid gold has particles that are close together, randomly arranged, and able to move and slide past one another, .