How many moles of $H_2O_2$ are required for the decolorization of $1$ mole of $KMnO_4$?

An aqueous solution of $18 \ g$ oxalic acid $(H_2C_2O_4 \cdot 2H_2O)$ is made up to $400 \ mL$. Calculate the volume of $0.1 \ M \ NaOH$ required to completely neutralize $50 \ mL$ of the above solution in $mL$.

Concentrated sulfuric acid is $95\%$ by weight and its density is $1.8 \ g \ cm^{-3}$. What volume of concentrated acid in $cm^3$ is required to prepare $4 \ L$ of $0.4 \ M \ H_2SO_4$ solution (in $.7$)?

What is the volume of $CO_2$ in liters produced at $STP$ by the complete decomposition of $9.85 \ g$ of $BaCO_3$? (Atomic mass of $Ba = 137$,$C = 12$,$O = 16$)

$25 \ mL$ of a solution of $Na_2CO_3$ having a specific gravity of $1.25$ required $32.9 \ mL$ of a solution of $HCl$ containing $109.5 \ g$ of the acid per litre for complete neutralization. Calculate the volume of $0.84 \ N$ $H_2SO_4$ that will be completely neutralized by $125 \ g$ of the $Na_2CO_3$ solution (in $mL$).

The volume of $0.02 \, M$ aqueous $HBr$ required to neutralize $10.0 \, mL$ of $0.01 \, M$ aqueous $Ba(OH)_2$ is $....... \, mL$ (Assume complete neutralization).