1. The problem is to describe the chemical reaction $\text{Ca} + 2\text{HNO}_3 \to \text{Ca(NO}_3)_2 + \text{H}_2$ in words. 2. This is a single displacement reaction where calcium (Ca) reacts with nitric acid (HNO3). 3. The formula shows that one atom of calcium reacts with two molecules of nitric acid. 4. Calcium displaces hydrogen from nitric acid, forming calcium nitrate $\text{Ca(NO}_3)_2$ and hydrogen gas $\text{H}_2$. 5. In words, the reaction is: "Calcium reacts with nitric acid to produce calcium nitrate and hydrogen gas."