The empirical formula of an acid is $CH_2O_2$. The probable molecular formula of the acid may be:

$A$ hydrocarbon contains $80\%$ carbon and its vapor density is $15$. What is the hydrocarbon?

Calculate the amount of aluminium present in $Al_2(SO_4)_3$ if the compound contains $4 \text{ g}$ of sulfur. [Molar mass of sulfur = $32 \text{ g/mol}$, Molar mass of $Al = 27 \text{ g/mol}$] (in $\text{ g}$)

An oxide of iron,which contains $69.9 \%$ iron and $30.1 \%$ dioxygen by mass,has the empirical formula:

$64 \, g$ of an organic compound contains $24 \, g$ of carbon,$8 \, g$ of hydrogen,and the rest oxygen. The empirical formula of the compound is

An organic compound weighing $500 \ mg$ produced $220 \ mg$ of $CO_2$ on complete combustion. The percentage composition of carbon in the compound is $..........\%$. $(nearest \ integer)$ $(Given \ molar \ mass \ in \ g \ mol^{-1} \ of \ C: 12, O: 16)$