Which of the following statements is most likely to be incorrect ?

Options

A. `Ti(NO_3_4` is a colourless compound
B. `[Cu(NC CH_3)_4]^(+) BF_4^(-)` is a colourles compound.
C. `[Cr(NH_3)_6]^(3+) 3Cl^(-)` is a coloured compound
D. `K_3[VF_6]` is a colourless compound

Explanation

To determine which statement is most likely to be incorrect, we will analyze each statement regarding the compounds mentioned.

### Step 1: Analyze Statement 1
**Statement 1:** Ti(NO₃)₄ is a colorless compound.

- **Analysis:** Titanium (Ti) in Ti(NO₃)₄ is in the +4 oxidation state. The electronic configuration of Ti is [Ar] 3d² 4s². In the +4 state, it loses all its 4s and 2 of its 3d electrons, resulting in [Ar] 3d⁰. Since there are no unpaired electrons in the d-orbitals, Ti(NO₃)₄ is indeed colorless.

### Step 2: Analyze Statement 2
**Statement 2:** [Cu(NH₃)₄]⁺ BF₄⁻ is a colorless compound.

- **Analysis:** Copper (Cu) in this complex is in the +1 oxidation state. The electronic configuration of Cu is [Ar] 3d¹⁰ 4s¹. In the +1 state, it loses the 4s electron, resulting in [Ar] 3d¹⁰. Since all d-orbital electrons are paired, [Cu(NH₃)₄]⁺ is also colorless.

### Step 3: Analyze Statement 3
**Statement 3:** [Cr(NH₃)₆]³⁺ + 3Cl⁻ is a colored compound.

- **Analysis:** Chromium (Cr) in this complex is in the +3 oxidation state. The electronic configuration of Cr is [Ar] 3d⁵ 4s¹. In the +3 state, it loses 3 electrons, resulting in [Ar] 3d³. The presence of unpaired electrons in the d-orbitals indicates that [Cr(NH₃)₆]³⁺ is colored.

### Step 4: Analyze Statement 4
**Statement 4:** K₃[VF₆] is a colored compound.

- **Analysis:** Vanadium (V) in K₃[VF₆] is in the +3 oxidation state. The electronic configuration of V is [Ar] 3d³ 4s². In the +3 state, it loses 3 electrons, resulting in [Ar] 3d². The presence of unpaired electrons in the d-orbitals suggests that K₃[VF₆] is also colored.

### Conclusion
- **Statement 1:** True (colorless)
- **Statement 2:** True (colorless)
- **Statement 3:** True (colored)
- **Statement 4:** True (colored)

The incorrect statement is **Statement 3**, which claims that [Cr(NH₃)₆]³⁺ is a colored compound, while it is indeed colored due to the presence of unpaired electrons.

### Final Answer
The most likely incorrect statement is **Statement 3**.

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