What volume of $H_2$ gas in liters at $1 \, \text{atm}$ pressure and $273 \, K$ temperature is required to reduce $21.6 \, g$ of boron trichloride $(BCl_3)$ (atomic weight of $B = 10.8$) to obtain boron?

$56.0 \ L$ of nitrogen gas is mixed with excess of hydrogen gas and it is found that $20 \ L$ of ammonia gas is produced. The volume of unused nitrogen gas is found to be $L$.

Concentrated nitric acid is labelled as $75 \%$ by mass. The volume in $mL$ of the solution which contains $30 \ g$ of nitric acid is $.............$ Given : Density of nitric acid solution is $1.25 \ g / mL$

Three substances $A$,$B$ and $C$ react to form $E$ and $D$ as shown: $2A + 3B + C \rightarrow 4D + 2E$. If the molar masses of $A, B, C$ and $D$ are $40, 30, 20$ and $15 \ g/mol$ respectively,and $570 \ g$ of a stoichiometric mixture of $A, B$ and $C$ is reacted,the maximum mass of $E$ obtained will be ............ $g$.

What is obtained when one mole of calcium phosphide is reacted with excess water?

The number of chlorine atoms in $1.98 \ g$ of $BaCl_2$ is ..... (Atomic weight of $Ba = 137$,$Cl = 35.5$)