How many kilograms of $CaCO_3$ must be heated to obtain $56$ kilograms of $CaO$? [Atomic masses: $Ca = 40, C = 12, O = 16$]

When $26 \ mL$ of $CO_2$ is passed over hot coke,the volume of $CO$ produced is .......... $mL$.

When $CO_2$ is bubbled through $0.205 \ mol$ of $Ba(OH)_2$,how many grams of $BaCO_3$ will be produced?

If the density of methanol is $0.793 \ kg \ L^{-1}$,what volume is needed to prepare $2.5 \ L$ of a $0.25 \ M$ solution (in $mL$)?

What weight of sodium hydroxide is required to neutralise $100 \ mL$ of $0.1 \ N - HCl$ (in $g$)?

For the gaseous reaction $H_2 + Cl_2 \rightarrow 2HCl$,if $40 \ mL$ of hydrogen reacts with chlorine,the volume of chlorine required and the volume of $HCl$ formed are respectively: