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

How much oxygen is required for complete combustion of $560 \ g$ of ethene? ................. $kg$

The molarity of $1 \ L$ orthophosphoric acid $(H_3PO_4)$ having $70 \%$ purity by weight (specific gravity $1.54 \ g \ cm^{-3}$) is $ . . . . . . $ $M$.
(Molar mass of $H_3PO_4 = 98 \ g \ mol^{-1}$)

The ratio of amounts of $H_2S$ needed to precipitate all the metal ions from $100 \ mL$ of $1 \ M$ $AgNO_3$ and $100 \ mL$ of $1 \ M$ $CuSO_4$ will be

What is the volume in $litres$ of the gas produced at $NTP$ by the reaction of $100 \ g$ of $CaC_2$ with water?
$CaC_2 + 2H_2O \rightarrow Ca(OH)_2 + C_2H_2$

$H_2$ evolved at $STP$ on complete reaction of $27 \ g$ of Aluminium with excess of aqueous $NaOH$ would be $............ \ L$