Why does a solid change to liquid when heat is added?
a) the spacing between particles decreases.
b)particles lose energy.
c)the spacing between particles increases.
d)the temperature decreases.

The correct answer is Option C.

Explanation:

Solid state: Here, the particles are closely arranged and do not have any intermolecular space between them and thus, they have stronger intermolecular forces of attraction.

Liquid state: Here, the particles are loosely arranged and have intermolecular space between them and thus, they have weaker intermolecular forces of attraction.

When solid state changes to liquid state, we provide heat and the particles move with a faster rate.

The spacing between the particles increases as this phase change occurs. This phase change is known as melting process.

Hence, the correct answer is Option C.

it is either c or d and i know for sure it is not a or b