Which element in the given below does not show variable valency ?

Options

A. Zn
B. Cu
C. Ni
D. Mn

Answer

To solve the question of which element among zinc, copper, nickel, and manganese does not show variable valency, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Variable Valency**:
- Variable valency refers to the ability of an element to exhibit more than one oxidation state. This is common in transition metals due to the involvement of d-orbitals in bonding.

2. **Identify the Elements**:
- The elements in question are zinc (Zn), copper (Cu), nickel (Ni), and manganese (Mn).

3. **Check the Electronic Configuration**:
- **Zinc (Zn)**: The electronic configuration is [Ar] 3d^10 4s^2. Zinc has a filled d-subshell (3d^10) and loses only the 2 electrons from the 4s orbital, leading to a stable +2 oxidation state.
- **Copper (Cu)**: The electronic configuration is [Ar] 3d^10 4s^1. Copper can lose either 1 or 2 electrons, resulting in +1 and +2 oxidation states.
- **Nickel (Ni)**: The electronic configuration is [Ar] 3d^8 4s^2. Nickel can exhibit +2 and +3 oxidation states.
- **Manganese (Mn)**: The electronic configuration is [Ar] 3d^5 4s^2. Manganese shows multiple oxidation states, including +2, +4, +6, and +7.

4. **Determine Which Element Does Not Show Variable Valency**:
- From the electronic configurations, we can see that zinc (Zn) only shows a +2 oxidation state and does not exhibit variable valency, while copper, nickel, and manganese do show variable valency.

5. **Conclusion**:
- Therefore, the element that does not show variable valency is **Zinc (Zn)**.

### Final Answer:
- The correct answer is **Zinc (Zn)**.