How many moles of $CO_2$ will be produced from $4 \ g$ carbon and $4 \ g$ oxygen in the following reaction?
$C + O_2 \rightarrow CO_2$

Complete combustion of ethane gives only gaseous products. In a closed vessel,$15 \ g$ of ethane and $112 \ g$ of $O_2$ were allowed to completely react. What is the total number of moles of gaseous substances present in the vessel at the end of the reaction?

When $5 \ mol$ of reactant $A$ reacts with $8 \ mol$ of reactant $B$ in a closed rigid container according to the reaction:
$3A_{(g)} + 4B_{(g)} \to 2C_{(g)}$
$10^{2} \ kJ$ of heat was liberated. The $\Delta_rH$ of the given balanced reaction in $kJ/mol$ at $300 \ K$ is: $[R = 8 \ J/mol \cdot K]$

Under similar conditions of pressure and temperature,$40 \, mL$ of slightly moist hydrogen chloride gas is mixed with $20 \, mL$ of ammonia gas,the final volume of gas at the same temperature and pressure will be ............. $mL$.

Percentage loss in mass on heating a mixture of $Na_2CO_3$ and $CaCO_3$ containing equal mass of the two components will be ............. $\%$

$A$ mixture of $100 \ mmol$ of $Ca(OH)_2$ and $2 \ g$ of $Na_2SO_4$ was dissolved in water and the volume was made up to $100 \ mL$. The mass of $CaSO_4$ formed and the concentration of $OH^{-}$ in the resulting solution,respectively,are:
(Molar mass of $Ca(OH)_2$,$Na_2SO_4$ and $CaSO_4$ are $74$,$142$ and $136 \ g \ mol^{-1}$ respectively; $K_{sp}$ of $Ca(OH)_2$ is $5.5 \times 10^{-6}$)