Question

$1.0$ mol of Fe reacts completely with $0.65$ mol of $O_2$ to give a mixture of only $FeO$ and $F{e}_2{O}_3.$ The mole ratio of ferrous oxide to ferric oxide is:

• A. $2:3$
• B. $4:3$
• C. $1:2$
• D. $2:7$

Answer 1

The correct option is B $4:3$

Let, moles of $FeO$ and $F{e}_2{O}_3$ in the mixture be a and b respectively, then ,we get following two equations.

For O - atoms

$a+3b=0.65\times 2=1.3$ ....(I)

For Fe-atoms

$a+2b=1$ .....(ii)

by solving (i) & (ii), we get $a:b=4:3$