Question

Assertion : The correct order of oxidising power is : $VO_2^+$ $< Cr_2O_7^{2-} < MnO_4^-$
Reason : The oxidation state of $Mn$ is $+7$.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (B)

The oxidation states of the given compounds are
VO$_{2}^{+}$ : x + 2(-2) = +1
$\Rightarrow $ x = +5
Cr₂O$_{7}^{2-}$ : 2x + 7(-2) = -2
$\Rightarrow $ 2x = +12
$\Rightarrow $ x = +6
MnO$_{4}^{-}$ : x + 4(-2) = -1
$\quad \quad \quad$ x = -1 + 8 = + 7
The correct order of oxidising power is
VO$_{2}^{+}$ < Cr₂O$_{7}^{2-}$ < MnO$_{4}^{-}$
due to the increasing stability of the lower species to which they are reduced.