A block of mass 'm' is held stationary against a rough wall by applying a force F as shown. Which one of the following statement is incorrect ?

A. Friction force = mg
B. F will not produce torque
C. Normal will not produce torque
D. Normal reaction = F

Options

A. Friction force = mg
B. F will not produce torque
C. Normal will not produce torque
D. Normal reaction = F

Answer

To solve the problem, we need to analyze the forces acting on the block and determine which statement is incorrect.

### Step-by-Step Solution:

1. **Identify the Forces Acting on the Block**:
- The weight of the block, \( mg \), acts downwards.
- The applied force \( F \) is acting horizontally against the wall.
- The normal force \( N \) acts perpendicular to the wall (horizontally).
- The frictional force \( f_s \) acts upwards to prevent the block from sliding down.

2. **Establish the Equilibrium Conditions**:
- Since the block is stationary, we can apply the conditions for equilibrium.
- In the vertical direction (y-direction):
\[ f_s = mg \]
- In the horizontal direction (x-direction):
\[ N = F \]

3. **Analyze Each Statement**:
- **Statement A**: Friction force = \( mg \)
- This is true because the frictional force must balance the weight of the block to keep it stationary.
- **Statement B**: \( F \) will not produce torque.
- This is true because the force \( F \) is applied at the center of mass of the block, which means the distance \( r \) from the pivot point (center of mass) is zero, resulting in zero torque.
- **Statement C**: Normal will not produce torque.
- This is also true for the same reason as above; the normal force acts at the center of mass.
- **Statement D**: Normal reaction = \( F \)
- This is true as we established from the equilibrium in the x-direction.

4. **Conclusion**:
- All statements A, B, C, and D are correct. Therefore, the question asks for the incorrect statement, and since all options are correct, the answer is that none of the statements are incorrect.

### Final Answer:
None of the statements are incorrect.