$19 \ g$ 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?

What will be the volume of $CO_2$ at $S.T.P.$ obtained by heating $9.85 \ g$ of $BaCO_3$? (Atomic mass of $Ba = 137$)

The normality of $0.04 \ M \ H_2SO_4$ is = ........ $N$

For the given series of reactions:
$NH_{3(g)} + O_{2(g)} \rightarrow NO_{(g)} + H_2O_{(l)}$
$NO_{(g)} + O_{2(g)} \rightarrow NO_{2(g)}$
To obtain the maximum mass of $NO_2$ from a given mass of a mixture of $NH_3$ and $O_2$,the ratio of the mass of $NH_3$ to $O_2$ should be:

How much of $NaOH$ is required to neutralize $1500 \ cm^3$ of $0.1 \ N \ HCl$ (At. wt. of $Na = 23$)?

The reduction of boron trichloride $(BCl_3)$ by hydrogen yields elemental boron (atomic mass $10.8 \ g/mol$). If $21.6 \ g$ of boron is produced,what is the volume of hydrogen gas required at $273 \ K$ and $1 \ atm$ pressure (in $L$)?