A child is upset because his ice cream is melting. He thinks he now has less dessert. Which of these explanations correctly states why the child is incorrect?

The ice cream melts because it is gaining heat and energy from an endothermic reaction but the mass of the ice cream never leaves the cone. This is because the Law of Conservation of Mass says that matter is not created nor destroyed. Where can the mass go exactly?

Nowhere because it stays in the cone and is the same amount of ice cream as before.