Calculate the amount of $NO_2$ required for producing $4$ moles of $HNO_3$ as per the chemical reaction,$3 NO_2 + H_2O \longrightarrow 2 HNO_3 + NO$. (in $g$)

Upon mixing equal volumes of aqueous solutions of $0.1 \, M \, HCl$ and $0.2 \, M \, H_2SO_4$,the concentration of $H^{+}$ in the resulting solution is $.... \, mol / L$.

$5 \, N$ $H_2SO_4$ was diluted from $1 \, L$ to $10 \, L$. The normality of the solution obtained is.....$N$.

$250 \ mL$ of a sodium carbonate solution contains $2.65 \ g$ of $Na_2CO_3$. If $10 \ mL$ of this solution is diluted to $1 \ L$,what is the concentration of the resultant solution (in $M$)?

$A$ car airbag is inflated by $N_2$ produced during rapid decomposition of $NaN_{3(s)}$. What will be the pressure of the inflated airbag if $130 \ g$ of $NaN_3$ is used (in $atm$)? The volume of the airbag is $10 \ L$ $(T = 300 \ K, R = 0.082 \ L \ atm \ K^{-1} \ mol^{-1})$.

The amount of calcium oxide produced on heating $150 \ kg$ of limestone ($75 \%$ pure) is $........... \ kg$ $(Nearest \ integer)$. Given: Molar mass (in $g \ mol^{-1}$) of $Ca = 40, O = 16, C = 12$.