select the correct answer. why does a solid change to liquid when heat is added? a. the spacing between…

Brief Explanations:

When heat is added to a solid, particles gain energy and start to move more freely. This causes the spacing between particles to increase, leading to a phase - change from solid to liquid. Options A and B are incorrect as particles gain energy and spacing increases, not decreases. Option D is incorrect as adding heat generally increases temperature during melting.

Answer:

C. The spacing between particles increases.