Question

$x$ gram of $FeO$ contains $112$ gram iron. Calculate mass of $F{e}_3{O}_4$ containing same amount of $O$ as present in $x$ gram $FeO$?

• A. $232gram$
• B. $116gram$
• C. $58gram$
• D. $464gram$

Answer 1

The correct option is B $116gram$

Molecular weight of $FeO=56+16=72$

$x$ $gm$ contains $112gm$ of iron.

$\therefore$ It contains $\frac{112\times 16}{56}=32gm$ of $O.$

Molar mass of $F{e}_3{O}_4=3\times 56+4\times 16=232gm$

It contains $32gm$ of $O$. (Given)

Hence mass of $Fe=\frac{3\times 56\times 32}{4\times 16}=84gm$

$\therefore$ Mass of $F{e}_3{O}_4$ containing $32gm$ of $O$ and $84gm$ of $Fe$ is, $32+84=116gm.$