The volume of $C{O}_2$ liberated at S.T.P and the quantity of heat energy liberated from the combustion of 2.3 g of ethyl alcohol is? 

$C_2{H}_{5}OH\left(l\right)+3O_2\left(g\right)\to 2C{O}_2\left(g\right)+3H_{2}O\left(l\right)+1367.2KJ/mole$  
46gms of $C_2{H}_{5}OH$ on combustion liberate $2\times 22.4lit$ of $C{O}_2$ at STP acid 1367.2 of energy
On combustion of 2.3g of $C_2{H}_{5}OH$  
$\frac{2.3}{46}\times 2\times 22.4=2.24lit$
Energy liberated $=\frac{2.3}{46}\times 1367.2=68.36 kj$