What volume of dioxygen is required for complete combustion of $2 \, \text{volumes}$ of acetylene gas at $NTP$?

What volume (in $mL$) of $0.1 \ M \ KOH$ solution is required for the complete neutralization of $20 \ mL$ of $0.1 \ M$ phosphorous acid $(H_3PO_3)$?

When $500 \, mL$ of a gaseous hydrocarbon is burned with sufficient $O_2$,it produces $2.5 \, L$ of $CO_2$ and $3.0 \, L$ of water vapor. What is the molecular formula of the hydrocarbon?

What is the weight of $50\%$ pure $HCl$ required to react completely with $100 \ g$ of $100\%$ pure limestone $(CaCO_3)$ (in $g$)?

At $300 \ K$ and $1 \ \text{atm}$ pressure,$10 \ mL$ of a hydrocarbon required $55 \ mL$ of $O_2$ for complete combustion,and $40 \ mL$ of $CO_2$ is formed. The formula of the hydrocarbon is

Volume of air needed for complete combustion of $10 \ L$ of $C_2H_4$ is :
$($Assume air contains $20\%$ of $O_2$ by volume$)$ (in $L$)