In electrolysis the mass deposited on an electrode is directly proportional to:

Options

A. current
B. square of current
C. concentration of solution
D. inverse of current

Answer

To solve the question regarding the relationship between the mass deposited on an electrode during electrolysis and various factors, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Electrolysis**: Electrolysis is a process where electrical energy is used to drive a non-spontaneous chemical reaction. During this process, ions move towards the electrodes, and mass is deposited on the electrodes.

2. **Refer to Faraday's Laws of Electrolysis**: According to Faraday's first law of electrolysis, the mass (m) of a substance deposited at an electrode is directly proportional to the quantity of electric charge (Q) passed through the electrolyte.

3. **Express Charge in Terms of Current and Time**: The charge (Q) can be expressed in terms of current (I) and time (t) using the formula:
\[ Q = I \times t \]
where:
- \( Q \) is the charge in coulombs,
- \( I \) is the current in amperes,
- \( t \) is the time in seconds.

4. **Relate Mass to Current and Time**: Substituting the expression for charge into the relationship from Faraday's law, we have:
\[ m \propto Q \implies m \propto I \times t \]
This indicates that the mass deposited is directly proportional to both the current and the time for which the current flows.

5. **Identify the Direct Proportionality**: Since the question asks for what the mass is directly proportional to, we can conclude that:
\[ m \propto I \]
This means that the mass deposited on the electrode is directly proportional to the current (I).

6. **Conclusion**: Therefore, the correct answer to the question is that the mass deposited on an electrode during electrolysis is directly proportional to the current.

### Final Answer:
The mass deposited on an electrode is directly proportional to the **current (I)**.