The incorrect statement for lanthanides among the following statements is :

Options

A. 4f and 5d orbitals are so close in energy that I t is very difficult to locate the exact position of electrons in lanthanides
B. most common stable oxidation state is +3
C. tripositive lanthanide ions have characteristic color depending on nature of group with which they combine to form compounds
D. some lanthanide ions absorb either in infrared or ultraviolet region of electromagnetic spectrum

Answer

To determine the incorrect statement regarding lanthanides, we need to analyze each statement provided. Here’s a step-by-step breakdown of the reasoning:

### Step 1: Understand the Nature of Lanthanides
- Lanthanides are f-block elements located in the periodic table. They consist of elements with atomic numbers from 57 (Lanthanum) to 71 (Lutetium).
- They have unique properties due to their electron configurations, particularly involving the 4f orbitals.

### Step 2: Analyze Each Statement
1. **Statement A**: "4f and 5d orbitals are so close in energy that it is very difficult to locate the exact position of electrons in lanthanides."
- **Analysis**: This statement is true. The 4f and 5d orbitals have similar energy levels, making it challenging to determine the exact electron configuration.

2. **Statement B**: "Most common stable oxidation state is plus three."
- **Analysis**: This statement is also true. The +3 oxidation state is the most stable for lanthanides, as they typically lose three electrons (two from 6s and one from 4f).

3. **Statement C**: "Tripositive lanthanide ions have characteristic color depending on the nature of the group with which they combine to form compounds."
- **Analysis**: This statement is true as well. Different lanthanide ions exhibit characteristic colors due to their electronic transitions.

4. **Statement D**: "Some lanthanide ions absorb either in the infrared or UV region of the electromagnetic spectrum."
- **Analysis**: This statement is incorrect. Lanthanide ions primarily absorb in the UV region and do not typically absorb in the infrared region.

### Step 3: Conclusion
- The incorrect statement among the options provided is **Statement D**.

### Final Answer
The incorrect statement for lanthanides is: **"Some lanthanide ions absorb either in the infrared or UV region of the electromagnetic spectrum."**

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