The answer is B.
A cannot be the answer is melting is a physical change. No chemical reaction took place.
B is the answer as it is a EXOTHERMIC REACTION so heat will be given off.
C cannot be the answer as dissolving is basically atoms becoming ions, not a chemical reaction whereby a reactant reacts with another reactant to form a product.
D cannot be the answer. Same reason as for why A is not the answer.
Cheers.
A.
because the nucleus contains protons and neutrons BUT neutrons are neutral and protons are positive, so the answer is A
<span>The valence electrons occur in the outer shell of the atom. </span>