Which among the following statement is wrong

Options

A. Electronic configuration of Gd`._(64)` is `4f^(7)5d^(1)6s^(2)`
B. `Ce^(4+)` is a good reductant
C. Actinoids exhibit higher oxidation states than Lanthanoids
D. Actinoids contraction is greater from element to element than Lanthanoid contraction

Answer

To determine which statement among the given options is wrong, we will analyze each statement one by one.

### Step 1: Analyze Statement A
**Statement A:** The electronic configuration of Gadolinium-64 is 4F7, 5D1, 6S2.

- Gadolinium (Gd) has an atomic number of 64.
- The electronic configuration can be derived as follows:
- The nearest noble gas before Gadolinium is Xenon (Xe), which has an atomic number of 54.
- After Xenon, we fill the orbitals:
- 6S2 (2 electrons)
- 5D1 (1 electron)
- 4F7 (7 electrons)
- Thus, the electronic configuration is indeed 4F7, 5D1, 6S2.
- **Conclusion:** This statement is correct.

### Step 2: Analyze Statement B
**Statement B:** Cerium 4+ is a good reductant.

- Cerium (Ce) has an atomic number of 58 and its electronic configuration is:
- Xenon (54) followed by 6S2, 5D1, and 4F1.
- In the +4 oxidation state, Cerium loses 4 electrons.
- The inert pair effect suggests that the +2 oxidation state is more stable due to poor shielding from the 4F electrons.
- Therefore, Cerium is more likely to act as an oxidizing agent rather than a reducing agent.
- **Conclusion:** This statement is incorrect.

### Step 3: Analyze Statement C
**Statement C:** Actinides exhibit higher oxidation states than lanthanides.

- Lanthanides involve the filling of 4F orbitals, while actinides involve filling 5F orbitals.
- Actinides can exhibit higher oxidation states due to the greater involvement of 5F orbitals and the ability to lose more electrons.
- This is a known trend in the chemistry of these elements.
- **Conclusion:** This statement is correct.

### Step 4: Analyze Statement D
**Statement D:** Actinoid contraction is greater than lanthanide contraction.

- Lanthanide contraction occurs due to poor shielding of the 4F electrons.
- Actinide contraction is more pronounced because the 5F orbitals are less effective at shielding the nuclear charge.
- Therefore, the contraction in actinides is indeed greater than in lanthanides.
- **Conclusion:** This statement is correct.

### Final Conclusion
Based on the analysis:
- Statement A: Correct
- Statement B: Incorrect (wrong statement)
- Statement C: Correct
- Statement D: Correct

Thus, the wrong statement is **Option B**: "Cerium 4+ is a good reductant."

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