iGCSE Physics (0625) 2.1.1 States of matter -Exam Style Questions Paper 2 - New Syllabus
▶️ Answer/Explanation
Detailed solution:
The state of a substance is determined by the arrangement and mobility of its particles. Solids have a fixed shape because their particles are held in a rigid lattice. In contrast, liquids and gases are fluids; they do not have a fixed shape and instead flow to take the shape of the part of the container they occupy. A liquid has a fixed volume but conforms to the container’s base, while a gas expands to fill the entire volume of its container. Since solids maintain their own shape regardless of the container, the only possible states for the sample described are gas and liquid. Thus, Option B is correct.
▶️ Answer/Explanation
Detailed solution:
In the diagram, arrow 1 points from solid to liquid, which is termed melting (or fusion).
Arrow 2 points from liquid to gas, which is correctly identified as boiling (or evaporation).
Arrow 3 indicates the reverse process from gas to liquid, known as condensation.
Finally, arrow 4 shows the transition from liquid back to solid, which is called freezing (or solidification).
Option C correctly matches these terms in the required sequence: melting, boiling, condensation, freezing.
Therefore, the precise terminology for these changes of state is found in option C.
▶️ Answer/Explanation
Detailed solution:
Condensation is the change of state from a gas to a liquid.
In a liquid, particles are arranged close together but are not in fixed positions; they can slide over one another.
This distinguishes them from solids, where particles vibrate about fixed points.
Therefore, the correct description of particles after condensation is that they are close together and slide over each other.
This matches Option A.