Question

The correct order of following $3d$ metal oxides, according to their oxidation number is

$\left(a\right)Cr{O}_3$
$\left(b\right)F{e}_2{O}_3$
$\left(c\right)Mn{O}_2$
$\left(d\right)V_2{O}_5$
$\left(e\right)C{u}_{2}O$

JEE MAINS 2021

• A. $\text{(d) >(a)>(b)>(c)>(e)}$
• B. $\text{(c)>(a)>(d)>(e)>(b)}$
• C. $\text{(a)>(c)>(d)>(b)>(e)}$
• D. $\text{(a) > (d) >(c)>(b)>(e)}$

Answer 1

The correct option is D $\text{(a) > (d) >(c)>(b)>(e)}$

Oxidation state of oxygen is -2.

$\begin{array}{cc}\text{Metal oxide}& \text{Oxidation number}\\ Cr{O}_3& +6\\ F{e}_2{O}_3& +3\\ Mn{O}_2& +4\\ V_2{O}_5& +5\\ C{u}_{2}O& +1\end{array}$

$a>d>c>b>e$

Hence, option (a) is correct.