What is the percentage atom economy when the formula weight of the product obtained is $70 \ u$ and the sum of the formula weights of the reactants is $140 \ u$ (in $\%$)?

What volume of $O_{2(g)}$ measured at standard condition will be formed by the action of $100 \ mL$ of $0.5 \ N \ KMnO_4$ on hydrogen peroxide in an acidic solution? The skeleton equation for the reaction is:
$KMnO_4 + H_2SO_4 + H_2O_2 \to KHSO_4 + MnSO_4 + O_2 + H_2O$
(Answer in $L$)

In an aqueous solution of $A_2B_3$,it undergoes complete ionization according to the reaction $A_2B_3 \rightleftharpoons 2A^{+3} + 3B^{-2}$. The concentration of $A^{+3}$ is equal to......

What is the normality of a $1 \, M$ solution of $H_3PO_4$?

Concentrated $HCl$ is $10 \, N$. How much volume of concentrated $HCl$ is required to prepare $1000 \, mL$ of $1 \, N$ $HCl$ by dilution?

Equal masses of ethane $(C_2H_6)$ and hydrogen $(H_2)$ are mixed in an empty container at $298 \ K$. The fraction of total pressure exerted by hydrogen is: