Question

Assertion : $E^{\circ}$ for $Mn ^{3+} / Mn ^{2+}$ is more positive than $Cr ^{3+} / Cr ^{2+}$
Reason : The third ionization energy of $Mn$ is larger than that of $Cr$.

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

Answer 1

Answer: (B)

$Mn$ has more oxidation potential than $Cr$. It is present below that $Cr$ in $ECS$ . So its reduction potential is less than $Cr$. $E _{\text {cell }}^{\circ}$ is more the third ionisation energy for $Mn$ is $3258\, kJ\, mol ^{-1}$ and for $Cr$ is $2994 \,kJ\, mol ^{-1}$. So both the statements are true but not correct explanation.