To neutralize $25 \, mL$ of $0.25 \, M$ $Na_2CO_3$ solution,how much volume of $0.5 \, M$ $HCl$ is required? (Note: The reaction is $Na_2CO_3 + 2HCl \rightarrow 2NaCl + H_2O + CO_2$)

Volume of water needed to mix with $10 \ mL$ of $10 \ N \ HNO_3$ to get $0.1 \ N \ HNO_3$ is ............ $mL$.

$A$ metal exists as an oxide with formula $M_{0.96} O$. Metal $M$ can exist as $M^{2+}$ and $M^{3+}$ in its oxide $M_{0.96} O$. The percentage of $M^{3+}$ in the oxide is nearly: (in $\%$)

The heat of combustion of methane is $-800 \ kJ \ mol^{-1}$. What is the heat of combustion for $4 \times 10^{-4} \ kg$ of methane?

When a hydrocarbon $A$ undergoes combustion in the presence of air,it requires $9.5$ equivalents of oxygen and produces $3$ equivalents of water. What is the molecular formula of $A$?

When $22.4 \, L$ of $C_4H_8$ at $STP$ is burnt completely,$89.6 \, L$ of $CO_2$ gas at $STP$ and $72 \, g$ of water are produced. The volume of the oxygen gas at $STP$ consumed in the reaction is closest to $.... \, L$