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

If $10$ volumes of dihydrogen gas react with $5$ volumes of dioxygen gas, how many volumes of water vapour would be produced?

What is the percent atom economy if the formula weight of reactants and the formula weight of products are $45 \ u$ and $35 \ u$ respectively (in $\%$)?

$x \ mg$ of pure $HCl$ was used to make an aqueous solution. $25.0 \ mL$ of $0.1 \ M$ $Ba(OH)_2$ solution is used when the $HCl$ solution was titrated against it. The numerical value of $x$ is . . . . . . $\times 10^{-1}$. (Nearest integer)
Given: Molar mass of $HCl$ and $Ba(OH)_2$ are $36.5$ and $171.0 \ g \ mol^{-1}$ respectively.

How many grams of $KMnO_4$ are required to prepare $1 \ L$ of a $1 \ N$ solution,if the compound is used as an oxidizing agent in an acidic medium (in $g$)?

What is the volume (in litres) of oxygen required at $STP$ to completely convert $1.5 \ mol$ of sulphur into sulphur dioxide?