The formula of a substance is $(CO)_x$. If its vapor density is $70$,find the value of $x$.

$A$ hydrocarbon contains $10.5 \,g$ of carbon and $1 \,g$ of hydrogen. If $2.4 \,g$ of this hydrocarbon occupies a volume of $1 \,L$ at $1 \,atm$ pressure and $127 \,^{\circ}C$ temperature,what is the molecular formula of the hydrocarbon?

The empirical formula of a compound is $CH_2O$ and its vapor density is $30$. The molecular formula of the compound is ......

Which of the following pairs of species has the same percentage of carbon?

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 $Fe = 56 \ g/mol$)

$A$ carbon compound contains $12.8 \%$ of carbon,$2.1 \%$ of hydrogen and $85.1 \%$ of bromine. The molecular weight of the compound is $187.9$. Calculate the molecular formula of the compound. (Atomic weight: $H=1.008, C=12.0, Br=79.9$)