Question

Complete combustion of 750 g of an organic compound provides 420 g of $C{O}_2$ and 210 g of $H_{2}O$.The percentage composition of carbon and hydrogen in organic compound is 15.3 and respectively.
(Rounded off to the nearest integer)

Answer 1

44 g of $C{O}_2$ contains 12 g carbon
So, 420 g of $C{O}_2\Rightarrow \frac{12}{44}\times 420$
$\Rightarrow \frac{1260}{11}g\text{carbon}=114.545g\text{carbon}$

So,$\Rightarrow \%\text{of carbon}=\frac{114.545}{750}\times 100\%\approx 15.3\%$

$18g{H}_{2}O\text{contains}\Rightarrow 2gH$
$210g{H}_{2}O\text{contains}\Rightarrow \frac{2}{18}\times 210=23.33gH$

So,$\%\text{of}H\Rightarrow \frac{23.33}{750}\times 100=3.11\approx 3\%$