$A$ mixture of $NO_2$ and $N_2O_4$ has a vapour density of $38.3$ at $270,^oC$. Calculate the number of moles of $NO_2$ in $100$ moles of the mixture.

To neutralize $10 \, mL$ of $M/5$ $NaOH$,the volume of $M/20$ $HCl$ required is......$mL$.

When $10 \ mol$ of $SO_2$ and $15 \ mol$ of $O_2$ are mixed and passed over a catalyst,$8 \ mol$ of $SO_3$ is formed. How many moles of $SO_2$ and $O_2$ remain unreacted?

$12 \ g$ of $Mg$ (atomic mass $24$) will react completely with acid to give:

Consider the reaction shown below where $6.1 \,g$ of benzoic acid is used to obtain $7.8 \,g$ of $m$-bromobenzoic acid. The percentage yield of the product is ....... .
(Round off to the Nearest integer) [Given : Atomic masses : $C = 12.0 \,u, H = 1.0 \,u, O = 16.0 \,u, Br = 80.0 \,u$]

Phosphoric acid $(H_3PO_4)$ is a tribasic acid and one of its salts is sodium dihydrogen phosphate $(NaH_2PO_4)$. What volume of $1 \ M$ $NaOH$ solution should be added to $12 \ g$ of sodium dihydrogen phosphate (mol. wt. $120$) to exactly convert it into trisodium phosphate $(Na_3PO_4)$? (Answer in $mL$)