Question

$11.2$ $g$ of $Fe$ completely reacts with $3.36$ $L$ of $O_2$ gas under standard conditions to form $F{e}_x{O}_y$. Thus, $x+y$ is :

Answer 1

Assuming Ideal gas behavior of $O_2$ gas,
Volume occupied by $1$ mol of gas = $22.4$ litres
No. of moles in $3.36$ litres of $O_2$ gas $=$ $\frac{3.36}{22.4}=\frac{3}{20}$ moles
Molar mass of $Fe=56$ gms
Moles of $Fe$ in $11.2$ gms = $\frac{1}{5}$ moles
So, $\frac{1}{5}Fe+\frac{3}{20}{O}_2\to cF{e}_x{O}_y$
Balancing the equation and no. of atoms,

$c\times x=\frac{1}{5}$

$c\times y=\frac{3}{10}$

where, $x$ and $y$ are integers and $x$ and $y$ have no common factor other than $1$,
thus, $c=\frac{1}{10},x=2,y=3$

Hence, $x+y=5$