$A$ protein $'A'$ contains $0.30\, \%$ of glycine (molecular weight $75$). The minimum molar mass of the protein $'A'$ is $.......\, \times 10^{3} \, g\, mol^{-1}$ [nearest integer]

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?

$20$ carat gold contains ...... $(\%)$ percent gold.

In the crystalline solid $MSO_{4} \cdot nH_{2}O$ of molar mass $250 \ g \ mol^{-1}$, the percentage of anhydrous salt is $64$ by weight. The value of $n$ is

$A$ $400 \ mg$ iron capsule contains $100 \ mg$ of ferrous fumarate,$(C_2H_2O_4)Fe$. The percentage of iron present in it is approximately $.......... \%$.

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