Assertion: `E^(@)` for `Mn^(3+)//Mn^(2+)` is more positive than `Cr^(3+)//Cr^(2+)`
Reason: The third ionisation energy of `Mn` is larger than that of `Cr`.

Options

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 expalanation of the assertion
C. if assertion is true, reason is false
D. both assertion and reason are false statements.

Answer

b

Explanation

It is known that the value of `E^(@)` becomes more negative down the series. As the chrominum is present below in electrochemical series than Mn, so Mn has more positive positive `E^(@)` value than Cr.
`{:( Mn to 3d^(2) 4s^(2), Mn^(2+) to 3d^(5)4s^(0)),(Cr to 3d^(5)4s^(1),Cr^(2+) to 3d^(4) 4s^(0)):}`
For elimination of one electron from `Mn^(2+)`more, energy is required due to its stable configuration, That is why third ionization, energy of Mn is larger than Cr.