Assuming fully decomposed, the volume of  ${\mathrm{CO}}_2$released at STP on heating 9.85 g of ${\mathrm{BaCO}}_3$ (Atomic mass of Ba = 137) will be

 ${\mathrm{BaCO}}_3\to \mathrm{BaO}+{\mathrm{CO}}_2\uparrow$

   1 mole                             1 mole

$\begin{array}{l}\mathrm{Molecular}\mathrm{weight}\mathrm{of}{\mathrm{BaCO}}_3=137+12+3\times 16=197\\ \because 197\mathrm{g} \mathrm{of} {\mathrm{BaCO}}_3\mathrm{produces}22.4\mathrm{L} {\mathrm{ofCO}}_2\mathrm{at}\mathrm{S}.\mathrm{T}.\mathrm{P}.\\ \therefore 9.85\mathrm{g}\text{\hspace{0.17em}\hspace{0.17em}of B}{\mathrm{aCO}}_3\mathrm{produces}\frac{22.4}{197}\times 9.85{\mathrm{CO}}_2=1.12\mathrm{L}{\mathrm{CO}}_2\mathrm{at}\mathrm{S}.\mathrm{T}.\mathrm{P}.\end{array}$