Number of hydrogen atoms per molecule of a hydrocarbon $A$ having $85.8 \%$ carbon is $...............$. (Given : Molar mass of $A = 84 \ g \ mol^{-1}$ )

What is the percentage of $H_2O$ in $Fe(CNS)_3 \cdot 3H_2O$?

$A$ compound containing $Xe$ and $F$ has $63.8\%$ of $Xe$ by mass. Calculate the oxidation number of $Xe$ in this compound.

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 $Fe = 56 \ g/mol$)

An organic compound with a molecular weight of $60$ contains $C = 20\%$,$H = 6.67\%$,and $N = 46.67\%$,with the remainder being oxygen. Upon heating,the solid residue gives a violet color with alkaline copper sulfate solution. Identify the compound.

$A$ hydrocarbon contains $80\%$ carbon and its vapor density is $15$. What is the hydrocarbon?