Which of the following has the highest percentage of hydrogen?

If two compounds have the same empirical formula but different molecular formulas,then their .......

On complete combustion,$0.492 \ g$ of an organic compound gave $0.792 \ g$ of $CO_2$. The $\%$ of carbon in the organic compound is $..................$ (Nearest integer)

In an $80 \, g$ compound,the masses of elements are $C = 24 \, g$,$H = 4 \, g$,and $O = 32 \, g$. Find its empirical formula.

In an analysis,the ratio of iodine to oxygen in a certain substance is $254:80$. What will be the formula of this substance? (Atomic mass $I = 127$,$O = 16$)

$A$ hydrocarbon contains $10.5 \, g$ of carbon and $1 \, g$ of hydrogen. If the volume of $2.4 \, g$ of this hydrocarbon is $1 \, L$ at $127 \, ^\circ C$ and $1 \, atm$ pressure,then the hydrocarbon is: