Analysis of a $60 \, g$ compound gives $C = 24 \, g$,$H = 4 \, g$,and $O = 32 \, g$. What is its empirical formula?

$0.5 \ g$ of an organic compound $(X)$ with $60 \%$ carbon will produce $........ \times 10^{-1} \ g$ of $CO_2$ on complete combustion.

What is the percentage by mass of oxygen in $NaOH$? (Atomic mass of $Na=23 \ u, O=16 \ u, H=1 \ u$)

Hemoglobin in red blood cells contains $0.33\%$ iron by mass. The molecular weight of hemoglobin is $67000$. What is the number of iron atoms present in each molecule of hemoglobin? (Atomic mass of $Fe = 56 \ g/mol$)

Complete combustion of $X$ g of an organic compound gave $0.25$ g of $CO_2$ and $0.12$ g of $H_2O$. If the percentage of carbon is $25\%$ and of hydrogen is $4.89\%$, then $X = \_\_\_\_ \times 10^{-3}$ g. (Nearest integer) (Molar mass of $C$, $H$ and $O$ are $12, 1$ and $16$ g mol$^{-1}$ respectively.)

The empirical formula of a compound is $C_2H_5O$ and its vapour density is $45$. What is the molecular formula of the compound?