Limestone breaks down on heating: $\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2$. What mass of quicklime, $\text{CaO}$, comes from $50\ \text{g}$ of limestone? ($\text{Ca} = 40$, $\text{C} = 12$, $\text{O} = 16$.)