States and Properties of Matter

Practice past-paper questions

Practise O/L exam questions on States and Properties of Matter with worked solutions

1. 2022 · Paper II · 5 marks
   Explain, using particle theory, why a gas fills the entire volume of its container while a liquid takes the shape of the container but keeps a fixed volume. Include a labelled particle diagram for each state.
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   In a GAS: particles are far apart, move rapidly and randomly, exert negligible attractive forces on each other. They spread to fill all available space — hence fill the container fully. In a LIQUID: particles are close together with moderate attractive forces. They can slide past each other (flow) so the liquid conforms to the container shape. The volume is fixed because particles cannot easily escape the attraction of neighbours. Diagram: Gas — particles spread throughout box; Liquid — particles close together, no fixed arrangement but with a flat surface at the top.
   Source: NIE O/L Science 2022 Paper II Q3

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