Volume of air needed for complete combustion of $10 \ L$ of $C_2H_4$ is :
$($Assume air contains $20\%$ of $O_2$ by volume$)$ (in $L$)

If equal masses of methane $(CH_4)$ and hydrogen $(H_2)$ are mixed in an empty container at $25\,^oC$,what is the fraction of the total pressure exerted by hydrogen?

$CaCO_3$ reacts with $HCl$ to produce $CaCl_2, CO_2$ and $H_2O$. The approximate mass (in $g$) of $CaCO_3$ required to react completely with $25 \ mL$ of $0.75 \ M \ HCl$ is (atomic mass of $Ca=40, C=12, O=16, Cl=35.5$ and $H=1$).

How many grams of $HCl$ are required to prepare $1500 \, mL$ of $0.1 \, N \, HCl$ aqueous solution?

The moles of methane required to produce $81 \ g$ of water after complete combustion is $.... \times 10^{-2} \ mol.$ [nearest integer]

What is the value of percent atom economy when reactants having a sum of formula weight $78 \ u$ result in the formation of a product with a formula weight of $65 \ u$ (in $\%$)?