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

An organic compound containing carbon and hydrogen has an empirical formula of $CH_2$. The mass of $1 \, L$ of this organic gas is equal to the mass of $1 \, L$ of $N_2$ gas at the same temperature and pressure. What is the molecular formula of the organic gas?

$0.765 \ g$ of an acid gives $0.535 \ g$ of $CO_2$ and $0.13 \ g$ of $H_2O$. The ratio of the percentage of $C$ and $H$ is:

The number of grams of oxygen in $32.2 \ g$ of $Na_2SO_4 \cdot 10H_2O$ is approximately (in $g$)

An organic compound on analysis gives the following data: $C = 57.82 \%$,$H = 3.6 \%$ and the rest is oxygen. Its vapour density is $83$. Calculate its molecular formula.

Calculate the molecular formula of an iron oxide,in which the mass percentages of iron and oxygen are $69.9$ and $30.1$,respectively.