# Question #ed5e2

Jun 27, 2017

A sublimination

#### Explanation:

Sublimination is the phase change is the movement from a solid directly to a gas.

When acid rain hit limestone the limestone undergoes a chemical reaction releasing carbon dioxide gas. So part of the solid goes directly to a gas.

However technically this is a chemical reaction not a physical phase change. Sublimination is the best of the answers provided but it is not really a correct answer.

An better example would be heating solid iodine which goes directly from the solid to the liquid phase.

Jul 2, 2017

The answer is: None of the above.

#### Explanation:

One of the acids in acid rain is nitric acid.

It reacts with limestone according to the chemical equation:

$\text{2HNO"_3"(aq)" + "CaCO"_3"(s)" → "Ca"("NO"_3)_2"(aq)" + "H"_2"O(l)" + "CO"_2"(g)}$

Sublimation, condensation, and evaporation are all physical changes.

The reaction with acid rain is a chemical change.

Thus, none of the options is correct.