Magnesium nitrate, $\text{Mg(NO}_3)_2$, decomposes on heating to produce a white solid plus a mixture of gases. Oxygen is one of the gases given off. $29.7\text{ g}$ of anhydrous magnesium nitrate is heated until the reaction has completely finished. Which mass of oxygen is produced?
- A$3.2\text{ g}$
- B$6.4\text{ g}$
- C$12.8\text{ g}$
- D$19.2\text{ g}$