iGCSE Chemistry Core- 1.1Solids, liquids and gases -Exam Style Questions Paper 1- New Syllabus
▶️ Answer/Explanation
Detailed solution:
The diagrams show three states: 1 = gas (particles far apart, random motion), 2 = liquid (particles close, random arrangement), 3 = solid (particles close, regular arrangement). When a solid (3) changes to a gas (1), this is sublimation. During this change, the particles gain energy and their motion increases significantly. Therefore, for change 3→1, energy increases and particle motion increases, which matches row C.
▶️ Answer/Explanation
Detailed solution:
When you heat a gas and keep the pressure steady, the particles move faster and spread apart, so the volume increases. On the flip side, if you squeeze a gas by increasing the pressure while keeping the temperature constant, the particles get forced closer together, making the volume decrease. Row C captures both relationships correctly: volume increases with temperature, and volume decreases with pressure.
▶️ Answer/Explanation
Detailed solution:
When a liquid freezes into a solid, the particles lose kinetic energy and the attractive forces between them pull them into a regular, fixed arrangement. They can no longer move past each other freely—they can only vibrate in fixed positions. So, their positions become fixed. The particles actually move closer together (not further apart), move slower (not faster), and the attractions become stronger (not weaker).