Answer:
The correct answer is D Vaporizing a substance.
It's chlorine, it's one of the few elements with 7 valence electrons
<span>In melting only one substance is involved and the liquid and solid are the same material. Heat is needed for melting to occur. Dissolving involves two materials; the resulting solution is a mixture of both. The dissolved substance is still present in the solution even though it can't be seen.</span>