Which of the following is not correct?

Explanation

To determine which of the following statements is not correct, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement 1:** "Aqueous solution of NaCl is an electrolyte."

- **Explanation:** An electrolyte is a substance that dissociates into ions when dissolved in water. When NaCl (sodium chloride) is dissolved in water, it dissociates into Na⁺ (sodium ions) and Cl⁻ (chloride ions). Since it produces ions in solution, it is indeed classified as an electrolyte.

### Step 2: Analyze the second statement
**Statement 2:** "Unit of electrochemical equivalent is gram coulomb."

- **Explanation:** The electrochemical equivalent (Z) is defined as the mass of a substance deposited or liberated at an electrode during electrolysis per unit charge passed. The formula relating mass (W) to charge (Q) is given by:
\[ W = Z \cdot Q \]
Rearranging gives:
\[ Z = \frac{W}{Q} \]
Here, W is in grams and Q is in coulombs, so the unit of Z is grams per coulomb (g/C), not gram coulomb (g·C). Therefore, this statement is incorrect.

### Step 3: Analyze the third statement
**Statement 3:** "In Nernst equation, n represents the number of electrons transferred in the reaction."

- **Explanation:** The Nernst equation relates the cell potential to the concentrations of the reactants and products. In the equation:
\[ E_{cell} = E^{\circ}_{cell} - \frac{RT}{nF} \ln Q \]
or
\[ E_{cell} = E^{\circ}_{cell} - \frac{0.0591}{n} \log Q \]
'n' indeed represents the number of electrons transferred in the redox reaction. Thus, this statement is correct.

### Step 4: Analyze the fourth statement
**Statement 4:** "The last statement is the same, so this is misprinting."

- **Explanation:** This statement suggests that the previous statement is correct and simply reiterates it. If the third statement is correct, then this statement is also correct.

### Conclusion
After analyzing all statements, the only incorrect statement is **Statement 2**: "Unit of electrochemical equivalent is gram coulomb."

### Final Answer
The statement that is not correct is **Statement 2**.

---