Which of the following statement is wrong for the d-block elements?

Options

A. They have general electronic configuration `(n-1)d^(1-10)ns^(0-2)`.
B. They generally exhibit variable valency.
C. Last electron enters in `(n-1)d` sub-shell in them.
D. They are placed from `3^(rd) to 6^(th)` period in modern periodic table.

Answer

To determine which statement is wrong for the d-block elements, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A**: "They have the general electronic configuration of n - 1 d¹⁻¹⁰ n = 0 to 2."
- **Analysis**: The general electronic configuration of d-block elements is indeed represented as n - 1 d¹⁻¹⁰ ns², where n is the principal quantum number. This statement is correct.

2. **Statement B**: "They generally exhibit variable valency."
- **Analysis**: d-block elements are known for exhibiting variable valency due to the involvement of d electrons in bonding. For example, transition metals like iron (Fe) can exhibit multiple oxidation states such as +2 and +3. This statement is also correct.

3. **Statement C**: "Last electron enters in n - 1 d sub-shell."
- **Analysis**: In d-block elements, the last electron indeed enters the (n - 1)d sub-shell before the ns sub-shell. This is due to the energy levels of the orbitals. This statement is correct.

4. **Statement D**: "They are placed from the third to sixth period of the modern periodic table."
- **Analysis**: This statement is incorrect. The d-block elements are actually placed from the fourth period to the sixth period in the modern periodic table. The 3d series starts from the fourth period, and the 4d and 5d series correspond to the fifth and sixth periods, respectively.

### Conclusion:
The wrong statement regarding the d-block elements is **Statement D**.

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