What fraction of $Fe$ exists as $Fe(III)$ in $Fe_{0.96}O$?
(Consider $Fe_{0.96}$ to be made up of $Fe(II)$ and $Fe(III)$ only)

Volume of air required to completely burn $10 \ L$ of $C_2H_4$ is ................ $L$ (assume all volumes are measured at the same temperature and pressure,and air contains $20\%$ oxygen by volume).

If a $100 \ mL$ solution contains $X \ g$ of $Na_2CO_3$ and its concentration is $Y \ M$,then $X$ and $Y$ are respectively ...............

How many grams of $NaOH$ will be required to prepare $250 \, mL$ of $0.1 \, M$ solution?

If $500 \ mL$ of $CaCl_2$ solution contains $3.01 \times 10^{22}$ chloride ions,the molarity of the solution will be: (in $M$)

$5 \ g$ of $NaOH$ was dissolved in deionized water to prepare a $450 \ mL$ stock solution. What volume (in $mL$) of this solution would be required to prepare $500 \ mL$ of $0.1 \ M$ solution?
Given: Molar Mass of $Na$,$O$,and $H$ is $23$,$16$,and $1 \ g \ mol^{-1}$ respectively.