$X \ g$ of nitrobenzene on nitration gave $4.2 \ g$ of $m-$dinitrobenzene. $X = ............ \ g$. $(nearest \ integer)$ [Given: molar mass (in $g \ mol^{-1}$) $C: 12, H: 1, O: 16, N: 14$]

What is the volume occupied by $0.5 \ mol$ of $CO_2$ at $STP$ (in $dm^3$)?

Amount of oxygen required for combustion of $1 \, kg$ of a mixture of butane and isobutane is ............. $kg$.

Find the weight in grams of carbon monoxide $(CO)$ that contains the same number of oxygen atoms as are present in $22 \ g$ of carbon dioxide $(CO_2)$.

$5 \ g$ of $NaOH$ was dissolved in deionized water to prepare a $450 \ mL$ stock solution. What volume (in $mL$) of this solution would be required to prepare $500 \ mL$ of $0.1 \ M$ solution?
Given: Molar Mass of $Na$,$O$,and $H$ is $23$,$16$,and $1 \ g \ mol^{-1}$ respectively.

The amount of arsenic pentasulphide that can be obtained when $35.5 \ g$ of arsenic acid $(H_3AsO_4)$ is treated with excess $H_2S$ in the presence of conc. $HCl$ (assuming $100\%$ conversion) is $.... \ mol$.