What is the volume in $dm^3$ occupied by $3 \ mol$ of ammonia gas at $STP$?

The stoichiometric reaction of $516 \ g$ of dimethyldichlorosilane with water results in a tetrameric cyclic product $X$ in $75 \%$ yield. The weight (in $g$) of $X$ obtained is. . . . . . . [Use,molar mass $(g \ mol^{-1})$: $H=1, C=12, O=16, Si=28, Cl=35.5$]

The right option for the mass of $CO_2$ produced by heating $20 \ g$ of $20 \%$ pure limestone is $........ \ g$ (Atomic mass of $Ca = 40$) $[CaCO_3 \stackrel{1200 \ K}{\longrightarrow} CaO + CO_2]$

$X$ litres of carbon monoxide is present at $STP$. It is completely oxidized to $CO_2$. The volume of $CO_2$ formed is $11.207$ litres. What is the value of $X$ in litres?

$A$ gaseous mixture contains $CH_4$ and $C_2H_6$ in equimolecular proportion. The weight of $2.24 \ L$ of this mixture at $S.T.P.$ is :- .............. $g$

What ratio by mass of $Ne$ and $CH_4$ should be mixed so that the partial pressure exerted by each gas is the same?