Question

Assertion: E⁰ for Mn³⁺/Mn²⁺ is more positive than Cr³⁺/Cr²⁺.

Reason : The third ionisation energy of Mn is larger than that of Cr.

(a) Both A and R are true and R is the correct explanation of A  

(b) Both A and R are true but R is not correct explanation of A 

(c) A is true but R is false  

(d) A and R are false

Answer 1

Correct option  (b) Both A and R are true but R is not correct explanation of A  

Explanation:

It is known that the value of E⁰ becomes more negative down the series. As chromium is present below in electrochemical series than Mn so Mn has more positive -E⁰ value than Cr.

For elimination of one electron from Mn²⁺ more energy is required due to its stable configuration. Thus, third ionisation energy of Mn is larger than Cr.