The correct order of following 3d metal oxides, according to their oxidation numbers is: (a) $\mathrm{CrO}_{3}$ (b) $\mathrm{Fe}_{2} \mathrm{O}_{3}$ (c) $\mathrm{MnO}_{2}$ (d) $\mathrm{V}_{2} \mathrm{O}_{5}$ (e) $\mathrm{Cu}_{2} \mathrm{O}$

(A) (a) $>$ (d) $>$ (c) $>$ (b) $>$ (e)

(B) (c) $>$ (a) $>$ (d) $>$ (e) $>$ (b)

(C) (d) $>$ (a) $>$ (b) $>$ (c) $>$ (e)

(D) (a) $>$ (c) $>$ (d) $>$ (b) $>$ (e)

JEE Main · 2021 · 25 Jul 2021 · Shift 1 · d and f Block Elements

The correct order of following 3d metal oxides, according to their oxidation numbers is:
(a)

CrO_{3}

(b)

Fe_{2} O_{3}

(c)

MnO_{2}

(d)

V_{2} O_{5}

(e)

Cu_{2} O

Answer: (A)

Oxygen is

- 2

in each oxide, so the metal oxidation number follows from the formula:

+ 6

Cr O_{3}

+ 3

F e_{2} O_{3}

+ 4

Mn O_{2}

+ 5

V_{2} O_{5}

and

+ 1

C u_{2} O

. Ranking these gives

Cr O_{3} > V_{2} O_{5} > Mn O_{2} > F e_{2} O_{3} > C u_{2} O

JEE Main · 2021 · 25 Jul 2021 · Shift 1 · Single correct option