The composition of a sample of wustite is $Fe_{0.93} O_{1.00}$. The percentage of iron in the form of $Fe^{3+}$ ion is nearly:

The normality of $1 \ M$ solution of $H_3PO_4$ will be.....$N$

To neutralize completely $20 \ mL$ of $0.1 \ M$ aqueous solution of phosphorous acid $(H_3PO_3)$,the volume of $0.1 \ M$ aqueous $KOH$ solution required is .......... $mL$.

On electrical decomposition of $150 \ mL$ dry and pure $O_2$,$10\%$ of $O_2$ gets changed to $O_3$. The volume of the gaseous mixture after the reaction and the volume of the remaining gas left after passing through turpentine oil will be,respectively:

$1.5 \ mol$ of $O_2$ combine with $Mg$ to form oxide $MgO$. The mass of $Mg$ (atomic mass $24$) that has combined is ............. $g$.

$4.4 \ g$ of an unknown gas occupies $2.24 \ L$ of volume at standard temperature and pressure. The gas may be