The correct statement is/are:

Options

A. Zirconium (Zr) and hafnium (Hf) have almost same size
B. Correct order of ionisation energy of coinage metals is Cu `gtAg` `ltAu`
C. Carbon atom in `C Cl_(4)` is more electronegative than carbon atom in `CF_(4)`
D. `Pb^(2+)` is more stable than `Pb^(4+)`

Explanation

To solve the question regarding which statements are correct, we will analyze each option one by one.

### Step-by-Step Solution:

**Step 1: Analyze Option A**
- **Statement:** Zirconium and Hafnium have almost the same size.
- **Analysis:** This statement is correct. Due to the lanthanide contraction, the atomic radii of zirconium (Zr) and hafnium (Hf) are very similar. The filling of the 4f subshell in hafnium does not effectively shield the outer electrons, leading to similar sizes.

**Conclusion for Option A:** Correct.

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**Step 2: Analyze Option B**
- **Statement:** The correct order of ionization energy of coinage metals is Cu > Ag > Au.
- **Analysis:** This statement is incorrect. The correct order of ionization energy is Au > Cu > Ag. The reasoning is that the 4s electron in copper is closer to the nucleus than the 5s electron in silver, making it easier to remove. In gold, the 4f electrons cause an increase in nuclear charge, making the 5s electron more tightly held compared to silver.

**Conclusion for Option B:** Incorrect.

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**Step 3: Analyze Option C**
- **Statement:** The carbon atom in CCl4 is more electronegative than the carbon atom in CF4.
- **Analysis:** This statement is also incorrect. In CF4, fluorine is more electronegative than chlorine, which means the carbon atom in CF4 is less positive (more electronegative) compared to the carbon in CCl4. Therefore, the carbon in CF4 is more electronegative than in CCl4.

**Conclusion for Option C:** Incorrect.

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**Step 4: Analyze Option D**
- **Statement:** Pb2+ is more stable than Pb4+.
- **Analysis:** This statement is correct. The inert pair effect causes the stability of lower oxidation states to increase down the group. Thus, Pb2+ is more stable than Pb4+, which tends to act as an oxidizing agent.

**Conclusion for Option D:** Correct.

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### Final Conclusion:
The correct statements are:
- Option A: Zirconium and Hafnium have almost the same size.
- Option D: Pb2+ is more stable than Pb4+.