The empirical formula of a compound is $CH_2O$ and its molecular mass is $180$. The molecular formula of this compound is .....

$116 \ g$ of a substance upon dissociation reaction,yields $7.5 \ g$ of hydrogen,$60 \ g$ of oxygen and $48.5 \ g$ of carbon. Given that the atomic masses of $H, O$ and $C$ are $1, 16$ and $12$ respectively. The data agrees with how many formulae of the following?
$(A)$ $CH_3COOH$
$(B)$ $HCHO$
$(C)$ $CH_3OOCH_3$
$(D)$ $CH_3CHO$

An organic compound contains $C$,$H$ and $S$. The minimum molecular weight of the compound containing $8\%$ sulphur is........$g\,mol^{-1}$ (atomic weight of $S = 32\,amu$)

$A$ compound contains $2.2 \ g$ of phosphorus and $1.24 \ g$ of sulfur. What is its empirical formula?

$A$ hydrocarbon has $C = 85.72\%$ and the remaining is $H$. The hydrocarbon is:

Haemoglobin contains $0.33 \%$ of iron by mass. The molecular mass of haemoglobin is $67200$. The number of iron atoms present in one molecule of haemoglobin is: (Atomic mass of $Fe = 56$)