How much volume of $1 \,N$ aqueous solution of $H_2SO_4$ should be taken, which will contain $0.2$ moles of $H_2SO_4$ (in $\,mL$)?

For preparing one litre $N/10$ solution of $H_2SO_4$,we need $H_2SO_4$.......$g$.

$19 \ g$ of a mixture containing $NaHCO_3$ and $Na_2CO_3$ on complete heating liberated $1.12 \ L$ of $CO_2$ at $STP$. The weight of the remaining solid was $15.9 \ g$. What is the weight (in $g$) of $Na_2CO_3$ in the mixture before heating?

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:

In the laboratory,chlorine is prepared by the reaction of manganese dioxide $(MnO_2)$ with aqueous hydrochloric acid $(HCl)$ as follows:
$4HCl_{(aq)} + MnO_{2(s)} \to 2H_2O_{(l)} + MnCl_{2(aq)} + Cl_{2(g)}$
How many grams of $HCl$ will react with $5.0 \ g$ of manganese dioxide (in $g$)?