If a sample of $8.3 \ mL$ of $H_2SO_4$ $(36 \ N)$ is diluted with $991.7 \ mL$ of water,what is the approximate concentration of the resulting solution (in $N$)?

Two elements $A$ and $B$ form $0.15 \ mol$ of $A_2 B$ and $AB_3$ type compounds. If $0.15 \ mol$ of both $A_2 B$ and $AB_3$ weigh equally,then the atomic weight of $A$ is $...$ times the atomic weight of $B$.

$A$ mixture of $NO_2$ and $N_2O_4$ has a vapour density of $38.3$ at $270,^oC$. Calculate the number of moles of $NO_2$ in $100$ moles of the mixture.

In dilute aqueous $H_2SO_4$,the complex diaquodioxalatoferrate$(II)$ is oxidized by $MnO_4^-$. For this reaction,the ratio of the rate of change of $[H^{+}]$ to the rate of change of $[MnO_4^-]$ is

Magnetite can be reduced with $CO$ to yield iron metal and carbon dioxide. Calculate the mass of magnetite (in $kg$) needed to obtain $4 \ kg$ of iron if the process is $80 \%$ efficient. [Atomic weight of $Fe$ and $O$ are $56 \ g$ and $16 \ g$,respectively]

The hardness of a water sample (in terms of equivalents of $CaCO_3$) containing $10^{-3} \ M \ CaSO_4$ is ................... $ppm$ (Molecular mass of $CaSO_4 = 136 \ g \ mol^{-1}$)