An organic compound contains $C = 74.0\%$,$H = 8.65\%$ and $N = 17.3\%$. Its empirical formula is:

The percentage of $Se$ in peroxidase anhydrous enzyme is $0.5\%$ by weight (atomic weight $= 78.4$). Then,the minimum molecular weight of peroxidase anhydrous enzyme is:

Complete combustion of $1.80 \, g$ of an oxygen-containing compound $(C_xH_yO_z)$ gave $2.64 \, g$ of $CO_2$ and $1.08 \, g$ of $H_2O$. The percentage of oxygen in the organic compound is

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

The percentage composition of $H, C$,and $O$ in $H_2C_2O_4$ is respectively:

At $STP$,$2.8 \, L$ of a gaseous substance weighs $5.5 \, g$. If the compound contains $N$ and $O$ atoms,its molecular formula will be ..............