The compound in which nickel has the lower oxidation states is :

Options

A. `Ni(CO)_(4)`
B. `(CH_(3)COO)_(2)Ni`
C. `NiO`
D. `NiCl_(2)(PPh_(3))_(2)`

Answer

To determine the compound in which nickel has the lowest oxidation state, we need to analyze the oxidation states of nickel in each of the given options.

### Step-by-Step Solution:

1. **Identify the Compounds**:
Let's assume the options are:
- A: Nickel carbonyl (Ni(CO)₄)
- B: Nickel acetate (Ni(CH₃COO)₂)
- C: Nickel oxide (NiO)
- D: Nickel chloride with triphenylphosphine (NiCl₂(PPh₃)₂)

2. **Calculate the Oxidation State of Nickel in Each Compound**:
- **Option A: Nickel Carbonyl (Ni(CO)₄)**
- Carbonyl (CO) is a neutral ligand.
- Therefore, the oxidation state of nickel (Ni) is 0.
- **Oxidation State of Ni = 0**

- **Option B: Nickel Acetate (Ni(CH₃COO)₂)**
- Acetate (CH₃COO⁻) has a charge of -1.
- There are 2 acetate ions, contributing a total charge of -2.
- Let the oxidation state of Ni be X.
- The equation becomes: X + 2(-1) = 0
- Solving gives: X - 2 = 0 → X = +2.
- **Oxidation State of Ni = +2**

- **Option C: Nickel Oxide (NiO)**
- Oxygen (O) has a charge of -2.
- Let the oxidation state of Ni be X.
- The equation becomes: X + (-2) = 0
- Solving gives: X - 2 = 0 → X = +2.
- **Oxidation State of Ni = +2**

- **Option D: Nickel Chloride with Triphenylphosphine (NiCl₂(PPh₃)₂)**
- Chlorine (Cl) has a charge of -1, and there are 2 Cl atoms contributing a total charge of -2.
- Triphenylphosphine (PPh₃) is neutral.
- Let the oxidation state of Ni be X.
- The equation becomes: X + 2(-1) + 0 = 0
- Solving gives: X - 2 = 0 → X = +2.
- **Oxidation State of Ni = +2**

3. **Compare the Oxidation States**:
- Option A: 0
- Option B: +2
- Option C: +2
- Option D: +2

4. **Conclusion**:
The compound in which nickel has the lowest oxidation state is **Option A: Nickel Carbonyl (Ni(CO)₄)**, where the oxidation state of nickel is 0.