An organic compound has an empirical formula $CH_2O$,its vapour density is $45$. The molecular formula of the compound is

$A$ compound has the following composition by weight: $Na = 18.60 \%$,$S = 25.80 \%$,$H = 4.02 \%$,and $O = 51.58 \%$. Assuming that all the hydrogen atoms in the compound are part of water of crystallisation,the correct molecular formula of the compound is:

Quantitative analysis of an organic compound $(X)$ shows the following percentage composition: $C: 14.5\%$,$Cl: 64.46\%$,and $H: 1.8\%$. The empirical formula mass of the compound $(X)$ is $.......... \times 10^{-1}$. (Given molar mass in $g \ mol^{-1}$ of $C: 12, H: 1, O: 16, Cl: 35.5$)

An organic compound is estimated through the Dumas method and is found to evolve $6$ moles of $CO_2$,$4$ moles of $H_2O$,and $1$ mole of nitrogen gas. The formula of the compound is

$A$ gaseous compound of nitrogen and hydrogen contains $12.5\%$ (by mass) of hydrogen. The density of the compound relative to hydrogen is $16$. The molecular formula of the compound is

Hemoglobin contains $0.34 \%$ of iron by mass. The number of $Fe$ atoms in $3.3 \ g$ of hemoglobin is. (Given : Atomic mass of $Fe$ is $56 \ u, N_A = 6.022 \times 10^{23} \ mol^{-1}$)