An organic substance $(80 \ g)$ on analysis was found to contain $C = 24 \ g$,$H = 4 \ g$,and $O = 32 \ g$. What is its empirical formula?

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 $Fe = 56$)

An organic compound weighing $500 \ mg$ produced $220 \ mg$ of $CO_2$ on complete combustion. The percentage composition of carbon in the compound is $..........\%$. $(nearest \ integer)$ $(Given \ molar \ mass \ in \ g \ mol^{-1} \ of \ C: 12, O: 16)$

Reduction of $7.2 \, g$ of a metal oxide yields $6.4 \, g$ of the metal. If the atomic mass of the metal is $128 \, g/mol$,the formula of the oxide is .....

An organic compound containing $C$, $H$, and $O$ has $13.13 \% H$, $52.14 \% C$, and $34.73 \% O$. Its molar mass is $46.068 \ g/mol$. What are its empirical and molecular formulae?

The correct sequence in decreasing order of the percentage of nitrogen in the given compounds is