Question

Calculate the volume of carbon dioxide produced (in L) on heating 20 g of pure limestone at STP.

Answer 1

$CaC{O}_{3\left(s\right)}\to CaO+C{O}_2\uparrow$
1 mol of $CaC{O}_3$ decomposes to 1 mol of $C{O}_2$.
100 g of $CaC{O}_3$ gives 44 g of $C{O}_2$ = 22.4 L of $C{O}_2$
10 g of limestone will give $C{O}_2=\frac{22.4\times 10}{100}=2.24\text{L}$