How much copper can be obtained from $100 \ g$ of copper sulfate $(CuSO_4)$ (in $g$)?

The percentage composition of carbon by mole in methane is ........... $ \% $

$A$ 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 mass percentage of nitrogen in histamine is

In which of the following pairs is the percentage of carbon the same?

On combustion,$0.210 \ g$ of an organic compound containing $C$,$H$,and $O$ gave $0.127 \ g$ $H_2O$ and $0.307 \ g$ $CO_2$. The percentages of hydrogen and oxygen in the given organic compound respectively are $:$