The $NaNO_3$ weighed out to make $50 \ mL$ of an aqueous solution containing $70.0 \ mg$ $Na^{+}$ per $mL$ is $...... \ g$.
(Rounded off to the nearest integer) [Given : Atomic weight in $g \ mol^{-1}$ - $Na : 23$; $N : 14$; $O : 16$]

$40\%$ of a mixture of $0.2 \ mol$ of $N_2$ and $0.6 \ mol$ of $H_2$ reacts to give $NH_3$ according to the equation:
$N_{2(g)} + 3H_{2(g)} \rightleftharpoons 2NH_{3(g)}$
at constant temperature and pressure. What is the ratio of the final volume to the initial volume of gases?

$A$ 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.

The volume of $0.1 \, M$ $H_2SO_4$ that is needed to completely neutralize $40 \, mL$ of $0.2 \, M$ $NaOH$ is $..... \, mL$.

What volume of Hydrogen gas,at $273 \ K$ and $1 \ atm$ pressure,will be consumed in obtaining $21.6 \ g$ of elemental boron (atomic mass $= 10.8$) from the reduction of boron trichloride by Hydrogen? (Answer in $L$)

At $NTP$,$40 \, mL$ of nitrogen reacts with hydrogen to form ammonia. According to the reaction $N_2 + 3H_2 \rightarrow 2NH_3$,the mass of ammonia formed will be ..... (in $, g$)