What is the volume (in litres) of oxygen at $STP$ required for complete combustion of $32 \,g$ of $CH_4$? (Molecular weight of $CH_4$ is $16$)

At constant temperature and pressure,the change in volume when $80\%\, 100\, mL$ of phosgene $(COCl_2)$ decomposes into $CO$ and $Cl_2$ is an increase of ............... $mL$.

The volume of air needed for complete conversion of $100 \ cm^3$ of $NO$ to $NO_2$ will be (assuming $20 \%$ $O_2$ by volume in air).
$2 NO_{(g)} + O_{2(g)} \rightarrow 2 NO_{2(g)}$ (in $cm^3$)

The chloride of a metal is $MCl_2$. The formula of its phosphate will be:

The density of a monobasic strong acid (Molar mass $24.2 \ g \ mol^{-1}$) is $1.21 \ kg \ L^{-1}$. The volume of its solution required for the complete neutralization of $25 \ mL$ of $0.24 \ M \ NaOH$ is $.............. \times 10^{-2} \ mL$ (Nearest integer).

If $0.2 \ mol$ of sulphuric acid is poured into $250 \ mL$ of water,calculate the concentration of the solution?