How many moles of $H_2O_2$ are required to decolorize $1$ mole of $KMnO_4$ (in $.5$)?

The normality of $0.3 \ M$ phosphorous acid $(H_3PO_3)$ is

The amount of carbon dioxide evolved upon complete combustion of $116 \ g$ of $n$-butane is
(Given : atomic mass in amu $H = 1, C = 12$ and $O = 16$) (in $g$)

Equal masses in grams of $H_2$, $N_2$, $Cl_2$, and $O_2$ are enclosed in cylinders separately. If these gases expand isothermally and reversibly by $10 \ dm^3$ at $300 \ K$, the work done by the gas is maximum for:

Volume of $4.4 \ g$ of $CO_2$ at $NTP$ is ............... $L$

Assuming complete decomposition,the volume of $CO_2$ released at $STP$ on heating $9.85 \ g$ of $BaCO_3$ (Atomic mass of $Ba = 137$) will be ................ $L$.