To neutralize $25 \, mL$ of $0.25 \, M$ $Na_2CO_3$ solution,how much volume of $0.5 \, M$ $HCl$ is required? (Note: The reaction is $Na_2CO_3 + 2HCl \rightarrow 2NaCl + H_2O + CO_2$)

$A$ $20 \ mL$ solution of $KMnO_4$ with a concentration of $1 \ N$ reacts with $20 \ mL$ of oxalic acid. The weight of oxalic acid in the $1 \ N$ solution is ......... $g$.

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 $g \ mol^{-1}$ - $Na : 23$; $N : 14$; $O : 16$]

$23 \ g$ of $Na$ will react with methyl alcohol to give:

Concentrated aqueous sulphuric acid is $98\% \ H_2SO_4$ by mass and has a density of $1.80 \ g \ mL^{-1}$. The volume of acid required to make $1 \ L$ of $0.1 \ M \ H_2SO_4$ solution is ........ $mL$.

If $10 \ g$ ($90 \%$ pure) limestone is heated,what volume of $CO_2$ in liters will be obtained at $NTP$?