Number of hydrogen atoms per molecule of a hydrocarbon $A$ having $85.8 \%$ carbon is $...............$. (Given : Molar mass of $A = 84 \ g \ mol^{-1}$ )

The empirical formula of a crystalline iron compound is $Fe_2(SO_4)_3$. It is used in water and sewage treatment to remove suspended impurities. The percentage composition of iron,sulfur,and oxygen in this compound is respectively......

The empirical formula of a hydrocarbon containing $80\%$ carbon and $20\%$ hydrogen is:

$0.5 \ g$ of an organic compound on combustion gave $1.46 \ g$ of $CO_2$ and $0.9 \ g$ of $H_2O$. The percentage of carbon in the compound is $...........$ ($NEAREST$ $INTEGER$). [$GIVEN$: Molar mass in $g \ mol^{-1}$: $C: 12, H: 1, O: 16$]

$A$ compound $X$ contains $32 \%$ of $A$,$20 \%$ of $B$,and the remaining percentage of $C$. Then,the empirical formula of $X$ is:
(Given atomic masses of $A = 64$,$B = 40$,$C = 32 \ u$)

An organic compound contains $C = 40\%$,$H = 13.33\%$,and $N = 46.67\%$. Its empirical formula is: