$A$ pure compound contains $2.4 \ g$ of $C$,$1.2 \times 10^{23}$ atoms of $H$,and $0.2 \ mol$ of oxygen atoms. Its empirical formula is

Find the empirical formula of an organic compound if it contains $18.6 \% C$,$1.55 \% H$,and $55.04 \% Cl$. (Atomic masses: $C=12$,$H=1$,$Cl=35.5$,$O=16$)

In a substance,the number of atoms of $Cr$ and $O$ are $4.8 \times 10^{10}$ and $9.6 \times 10^{10}$ respectively. The empirical formula of the substance is .......

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 $\text{ g}$)

The molecular formula of potash alum is

Calculate the percentage composition of the following elements:
$(a)$ Sulphur in $CN_4H_4S$
$(b)$ Carbon in $C_2H_4O_2$
$(c)$ Nitrogen in $CN_2H_2O$
$(d)$ Hydrogen in $C_6H_6$
Given atomic masses: $C = 12, H = 1, O = 16, N = 14, S = 32$.