The `EMF` of `Ni-Cad` battery is dependent of `:`

Options

A. `Cd(OH)_(2)`
B. `Ni(OH)_(2)`
C. `overset(c-)(O)H`
D. None of these

Explanation

To determine the factors on which the EMF (Electromotive Force) of a nickel-cadmium (Ni-Cad) battery depends, we can analyze the components and reactions occurring within the battery.

### Step-by-Step Solution:

1. **Identify the Components of the Ni-Cad Battery**:
- The battery consists of cadmium (Cd) at the anode and nickel oxide (NiO) at the cathode.
- The electrolyte is a solution of potassium hydroxide (KOH).

2. **Understand the Reactions**:
- At the anode, cadmium is oxidized to cadmium hydroxide (Cd(OH)₂) and releases electrons:
\[ \text{Cd} \rightarrow \text{Cd(OH)}_2 + 2e^- \]
- At the cathode, nickel oxide is reduced to nickel hydroxide (Ni(OH)₂):
\[ \text{NiO} + 2\text{OH}^- + 2e^- \rightarrow \text{Ni(OH)}_2 \]

3. **Overall Reaction**:
- When we combine the anodic and cathodic reactions, the hydroxide ions (OH⁻) cancel out, leading to the overall reaction:
\[ \text{Cd} + \text{NiO} + \text{H}_2\text{O} \rightarrow \text{Cd(OH)}_2 + \text{Ni(OH)}_2 \]
- Here, all reactants and products are in solid state or precipitates.

4. **Analyze the Dependence on Ionic Concentration**:
- The EMF of a battery is influenced by the concentration of ionic species in the electrolyte.
- In this case, since the overall reaction does not involve any change in the concentration of ions in solution (as all species are solids), the EMF does not depend on the concentrations of Cd(OH)₂, Ni(OH)₂, or OH⁻ ions.

5. **Conclusion**:
- Since the EMF does not depend on any of the given options (Cd(OH)₂, Ni(OH)₂, OH⁻), the correct answer is:
**None of them (Option D)**.