In $Fe_{0.96}O$,$Fe$ is present in $+2$ and $+3$ oxidation states. What is the mole fraction of $Fe^{2+}$ ions in the compound?

$40 \ mL$ of $0.1 \ N$ $KMnO_4$ is equivalent to $30 \ mL$ of $KHC_2O_4$ solution. How many $mL$ of $0.1 \ N$ $KOH$ are required to titrate $60 \ mL$ of the same $KHC_2O_4$ solution?

When oxygen is heated in the presence of a catalyst,$15 \%$ of it is converted into ozone. How many grams of oxygen are required to produce $33.6 \, L$ of $O_3$ at $STP$?

The $NaNO_3$ weighed out to make $50 \ mL$ of an aqueous solution containing $70.0 \ mg$ $Na^{+}$ per $mL$ is $...... \ g$.
(Rounded off to the nearest integer) [Given : Atomic weight in $g \ mol^{-1}$ - $Na : 23$; $N : 14$; $O : 16$]

If $1 \, mole$ of $H_3PO_x$ is completely neutralized by $80 \, g$ of $NaOH$,select the correct statement :-

The volume in $mL$ of $0.1 \ M$ solution of $NaOH$ required to completely neutralize $100 \ mL$ of $0.3 \ M$ solution of $H_3PO_3$ is