What volume of hydrogen gas at $STP$ would be liberated by the action of $50 \text{ mL}$ of $H_2SO_4$ of $50\%$ purity (density = $1.3 \text{ g mL}^{-1}$) on $20 \text{ g}$ of zinc (in $L$)? Given: Molar mass of $H, O, S, Zn$ are $1, 16, 32, 65 \text{ g mol}^{-1}$ respectively.

If $0.50 \ mol$ of $CaCl_2$ is mixed with $0.20 \ mol$ of $Na_3PO_4$,the maximum number of moles of $Ca_3(PO_4)_2$ which can be formed,is

$10 \ g$ of hydrogen and $64 \ g$ of oxygen were filled in a steel vessel and exploded. The amount of water produced in this reaction will be ............... $mol$.

Dinitrogen and dihydrogen react with each other to produce ammonia according to the following chemical equation: $N_{2(g)} + 3H_{2(g)} \to 2NH_{3(g)}$
$(i)$ Calculate the mass of ammonia produced if $2.00 \times 10^3 \ g$ of dinitrogen reacts with $1.00 \times 10^3 \ g$ of dihydrogen.
$(ii)$ Will any of the two reactants remain unreacted?
$(iii)$ If yes,which one and what would be its mass?

$0.5 \ mol$ of $H_2SO_4$ is mixed with $0.2 \ mol$ of $Ca(OH)_2$. What is the maximum number of moles of $CaSO_4$ formed?

$250 \ mL$ of $0.5 \ M \ NaOH$ was added to $500 \ mL$ of $1 \ M \ HCl$. The number of unreacted $HCl$ molecules in the solution after complete reaction is $...... \times 10^{21}$. (Nearest integer) $(N_{A} = 6.022 \times 10^{23})$