Identify the incorrect statement from the following:

Options

A. Zirconium and hafnium have identical radii of 160pm and 159pm, respectively as a consequence of lanthnoid contraction.
B. Lanthanoids reveal only +3 oxidation state
C. The lanthanoid ions other than the `f^0` type and the 1f^(14)` type are all paramagnetic
D. The overall decrease in atomic and ionic radii from lanthanum to luetetium is called lanthanoid contraction

Answer

To identify the incorrect statement from the given options regarding lanthanides, we can analyze each statement step by step.

### Step-by-Step Solution:

1. **Understanding the Elements**:
- The first statement mentions that zirconium (Zr) and hafnium (Hf) are almost equal in size. This is due to the phenomenon known as lanthanide contraction, which occurs because of the poor shielding effect of the 4f electrons in lanthanides.

**Hint**: Remember that lanthanide contraction affects the size of elements in the same group.

2. **Analyzing the First Statement**:
- The first statement is correct. Lanthanide contraction leads to similar sizes of Zr and Hf despite their positions in the periodic table.

**Hint**: Check the periodic table for the positions of Zr and Hf to understand their similarities.

3. **Analyzing the Second Statement**:
- The second statement claims that lanthanides only exist in the +3 oxidation state. This is incorrect because lanthanides can also exhibit +2 and +4 oxidation states.

**Hint**: Recall the common oxidation states of lanthanides and consider the exceptions.

4. **Analyzing the Third Statement**:
- The third statement suggests that only lanthanides with f0 and f14 configurations are paramagnetic. This is incorrect because any lanthanide with unpaired electrons is paramagnetic, regardless of whether they have f0 or f14 configurations.

**Hint**: Review the electron configurations of lanthanides to determine which ones have unpaired electrons.

5. **Conclusion**:
- The incorrect statement is the second one, which claims that lanthanides only exist in the +3 oxidation state.

### Final Answer:
The incorrect statement is: "Lanthanides exist only in the +3 oxidation state."