State True or false
The mass of a substance deposited on the cathode or anode during electrolysis is given as `m=QM//Fn`.

Explanation

To determine whether the statement "The mass of a substance deposited on the cathode or anode during electrolysis is given as m = QM/Fn" is true or false, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Statement**:
The statement claims that the mass (m) of a substance deposited during electrolysis can be expressed in the form of m = QM/Fn, where Q is the charge, M is the molar mass of the substance, and F is Faraday's constant, while n is the number of electrons transferred (valency).

2. **Faraday's First Law 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. This can be mathematically expressed as:
\[ m = Z \times Q \]
where Z is the electrochemical equivalent of the substance.

3. **Electrochemical Equivalent (Z)**:
The electrochemical equivalent (Z) can be defined as:
\[ Z = \frac{M}{nF} \]
where M is the molar mass of the substance, n is the number of moles of electrons exchanged (valency), and F is Faraday's constant (approximately 96500 C/mol).

4. **Substituting Z into the Equation**:
Now, substituting Z into the equation for mass:
\[ m = Z \times Q = \left(\frac{M}{nF}\right) \times Q \]
This can be rearranged to:
\[ m = \frac{MQ}{nF} \]
which matches the form given in the statement m = QM/Fn.

5. **Conclusion**:
Since we have derived that the mass deposited can indeed be expressed as m = QM/Fn, we conclude that the statement is true.

### Final Answer:
**True**