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4. d and f- block elements — Chemistry STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceChemistry4. d and f- block elements1 Mark
MCQ
Assertion : $E^o$ 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 $Cr$.

  • ✓
    If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
  • B
    If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
  • C
    If the Assertion is correct but Reason is incorrect.
  • D
    If both the Assertion and Reason are incorrect.
✓

Answer

Correct option: A.
If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
a
Reduction potential of $Mn^{3+}$ is more than $Cr^{3+}$. So, $Mn^{3+}$ is easily reduced in comparision with $Cr^{3+}$ or $Cr^{2+}$ is easily oxidised than $Mn^{2+}$. Hence $Mn^{2+}$ will lose electrons with difficulty or ionisation potential of $Mn^{2+}$ is more than $Cr^{2+}$. Both $A$ and $R$ are true.

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