Question

Which of the following is/are not oxidising agents in acidic medium?

• A. $Mo{O}_3$
• B. $W{O}_3$
• C. Both (a) and (b)
• D. $C{r}_2{O}_7^{2-}$

Answer 1

The correct option is C Both (a) and (b)

In d-block, higher oxidation states are favoured by the heavier elements​ because it is easier to remove valence electrons.
Stability of higher oxidation state increase down the group.
Stability order:
$Mo\left(VI\right)\&W\left(VI\right)>Cr\left(VI\right)$

Hence, due to stability of +6 oxidation state of Mo and W , they are not oxidising agents.

Dichromate ion $\left(C{r}_2{O}_7^{2-}\right)$ in acidic medium is a strong oxidising agent​.

Hence, option (d) is correct.