The molar mass of caffeine is $194$. It contains $28.9\%$ of nitrogen by mass. The number of nitrogen atoms in one molecule of caffeine is:

The empirical formula of a compound is $CH_2O$ and its molecular weight is $120$. The molecular formula of the compound is:

An organic compound contains $49.3\%$ carbon,$6.84\%$ hydrogen and its vapour density is $73$. The molecular formula of the compound is:

An organic compound contains carbon,hydrogen,and oxygen. Its elemental analysis gives $38.71 \%$ of $C$ and $9.67 \%$ of $H$. The empirical formula of the compound would be $:-$

$A$ gaseous compound of nitrogen and hydrogen contains $12.5\%$ (by mass) of hydrogen. The density of the compound relative to hydrogen is $16$. The molecular formula of the compound is

Complete combustion of $750 \ g$ of an organic compound provides $420 \ g$ of $CO_2$ and $210 \ g$ of $H_2O$. The percentage composition of carbon and hydrogen in the organic compound is $15.3$ and ............. respectively. (Round off to the Nearest Integer)