To a $25 \, mL$ of $H_2O_2$ solution,an excess of acidified solution of $KI$ was mixed. The liberated $I_2$ required $20 \, mL$ of $0.3 \, M$ hypo $(Na_2S_2O_3)$ solution for neutralization. The volume strength of $H_2O_2$ is......$mL$.

How many liters of $H_2$ gas will be evolved at $STP$ by the reaction of zinc metal with $500 \, mL$ of $0.5 \, N \, HCl$?

The amount of $50\% \ (w/w)$ solution of hydrochloric acid required to react with $200 \ g$ of $CaCO_3$ would be (in $g$)

The number of millimoles and milliequivalents of $Ba(OH)_2$ in $0.2 \, L$ of $0.2 \, M \, Ba(OH)_2$ solution are respectively:

An unknown chlorohydrocarbon has $3.55\%$ of chlorine. If each molecule of the hydrocarbon has one chlorine atom only,the number of chlorine atoms present in $1\,g$ of chlorohydrocarbon is (Atomic wt. of $Cl = 35.5\,u$; Avogadro constant $= 6.023 \times 10^{23}\,mol^{-1}$)

How many litres of oxygen (at $STP$) are required for complete combustion of $39 \ g$ of liquid benzene?
(Atomic weights: $C=12, O=16, H=1$)