NEET2006ChemistryClassification of Elements and Periodicity in PropertiesActual
Assertion : E^ 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 .
Options
- AIf both assertion and reason are true and reason is the correct explanation of the assertion
- BIf both assertion and reason are true but reason is not the correct explanation of the assertion
- CIf assertion is true, but reason is false
- DBoth assertion and reason are false statements.
Correct answer
B. If both assertion and reason are true but reason is not the correct explanation of the assertion
Step-by-step solution
It is known that the value of E^ becomes more negative down the series. As the chromium is present below in electrochemical series than Mn , so Mn has more positive E^ value than Cr . array ll Mn 3 d^5 4 s^2, & Mn ²⁺ 3 d^5 4 s^0 Cr 3 d^5 4 s^1, & Cr ²⁺ 3 d^4 4 s^0 array 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 .