The reaction scheme illustrates two consecutive reactions beginning with element Q. Element Q is either calcium or barium. $\text{element Q} \xrightarrow[\text{1}]{\text{heat with oxygen}} \text{compound R}$ $\text{element Q} \xrightarrow[\text{2}]{\text{add to water}} \text{compound R}$ Element Q produces a nitrate that is less thermally stable than strontium nitrate. Which compound is R?
- A$\text{CaO}$
- B$\text{Ca(OH)}_2$
- C$\text{BaO}$
- D$\text{Ba(OH)}_2$