Which of the following is not an application of electrochemical series ?

Options

A. To compare the relative oxidising and reducing power of substance
B. To predict evolution of hydrogen gas on reaction of metal with acid
C. To predict spontaneity of a redox reaction
D. To calculate the amount of metal deposited on cathode

Answer

To solve the question "Which of the following is not an application of electrochemical series?", we need to analyze the applications of the electrochemical series and identify which one does not belong.

### Step-by-Step Solution:

1. **Understanding the Electrochemical Series**:
The electrochemical series is a list of standard electrode potentials (SRP) of various half-reactions. It helps in predicting the behavior of different substances in redox reactions.

2. **Identifying Applications**:
The electrochemical series has several applications:
- **Comparing Oxidizing and Reducing Agents**: The series allows us to determine which substances are better oxidizers or reducers based on their SRP values.
- **Predicting Hydrogen Gas Evolution**: It helps in predicting whether a metal can displace hydrogen from acids based on its position in the series.
- **Predicting Spontaneity of Redox Reactions**: The series can be used to determine whether a redox reaction will occur spontaneously by comparing the SRP values of the reactants.
- **Calculating Amount of Metal Deposited on Cathode**: While the electrochemical series can help identify which reactions can occur, it does not directly provide a method to calculate the exact amount of metal deposited on the cathode.

3. **Analyzing the Options**:
- If the options given in the question include the applications mentioned above, we need to find the one that does not fit.
- The application that states "calculating the amount of metal deposited on cathode" is not a direct application of the electrochemical series, as it requires additional information and calculations (like Faraday's laws of electrolysis).

4. **Conclusion**:
Based on the analysis, the correct answer is that the application which is not related to the electrochemical series is "to calculate the amount of metal deposited on cathode".

### Final Answer:
The application that is not an application of the electrochemical series is: **"to calculate the amount of metal deposited on cathode."**