The unit of electrochemical equivalent is

Options

A. gm `"ampere"^(-1)`
B. gm/coulomb
C. gm-ampere
D. coulomb/gram.

Explanation

To determine the unit of electrochemical equivalent, we can follow these steps:

### Step-by-Step Solution:

1. **Definition of Electrochemical Equivalent (Z)**:
The electrochemical equivalent is defined as the mass of a substance deposited when a current of one ampere is passed for one second.

2. **Understanding Current and Time**:
When a current of one ampere flows for one second, the quantity of electricity (Q) can be calculated using the formula:
\[ Q = I \times t \]
Here, \(I = 1 \, \text{A}\) and \(t = 1 \, \text{s}\), so:
\[ Q = 1 \, \text{C} \, (\text{coulomb}) \]

3. **Formula for Electrochemical Equivalent**:
The electrochemical equivalent (Z) can be expressed as:
\[ Z = \frac{w}{Q} \]
Where \(w\) is the mass of the substance deposited (in grams) and \(Q\) is the quantity of electricity (in coulombs).

4. **Substituting Values**:
Since we established that \(Q = 1 \, \text{C}\), we can rewrite the equation as:
\[ Z = \frac{w}{1 \, \text{C}} = w \, \text{(in grams)} \]

5. **Unit of Electrochemical Equivalent**:
Therefore, the unit of electrochemical equivalent (Z) is grams per coulomb:
\[ \text{Unit of } Z = \frac{\text{grams}}{\text{coulomb}} = \text{grams/C} \]

6. **Conclusion**:
The final answer is that the unit of electrochemical equivalent is grams per coulomb (g/C).