Magnesium nitrate, $\text{Mg(NO}_3)_2$, breaks down when heated to produce a white solid and a mixture of gases. One of the gases given off is an oxide of nitrogen, $X$. $7.4\ \text{g}$ of anhydrous magnesium nitrate is heated until no further change takes place. What mass of $X$ is formed?
- A$1.5\ \text{g}$
- B$2.3\ \text{g}$
- C$3.0\ \text{g}$
- D$4.6\ \text{g}$