Consider the following statements:
(I) La`(OH)_(3)` is the least basic among the hydroxides of Ianthanoids.
(II) `Zr^(4+)` and `Hf^(4+)` possess almost same ionic radii.
(III) `Cr^(4+)` can act as an oxidising agent .
which of the above statement is/ are true?

Options

A. I and III
B. II and III
C. II only
D. I and II

Explanation

To determine which of the statements are true, let's analyze each one step by step.

### Step 1: Analyze Statement I
**Statement:** La(OH)₃ is the least basic among the hydroxides of lanthanoids.

**Analysis:**
Lanthanoid hydroxides generally increase in basicity from La(OH)₃ to Lu(OH)₃. La(OH)₃ is actually the most basic hydroxide among lanthanoids due to the larger ionic radius and lower charge density, which leads to weaker interactions with hydroxide ions. Therefore, this statement is **false**.

### Step 2: Analyze Statement II
**Statement:** Zr⁴⁺ and Hf⁴⁺ possess almost the same ionic radii.

**Analysis:**
Zirconium (Zr) and Hafnium (Hf) are in the same group of the periodic table and exhibit similar chemical properties. Due to the lanthanoid contraction, the ionic radii of Zr⁴⁺ and Hf⁴⁺ are indeed very similar. Thus, this statement is **true**.

### Step 3: Analyze Statement III
**Statement:** Cr⁴⁺ can act as an oxidizing agent.

**Analysis:**
Chromium can exist in multiple oxidation states, including +4 and +6. Cr⁴⁺ is less stable and can be reduced to Cr³⁺, which means it can gain electrons. Therefore, Cr⁴⁺ can act as an oxidizing agent by accepting electrons and being reduced. This statement is **true**.

### Conclusion
Based on the analysis:
- Statement I is **false**.
- Statement II is **true**.
- Statement III is **true**.

Thus, the true statements are II and III.

### Final Answer:
The true statements are II and III.

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