A cubical block of side 'a' is held at rest, against a rough vertical wall by applying a force `F` acting along the centre. The mass of the block is `m`. Taking acceleration due to gravity as 'g' , determine
`(i)` The minimum coefficient of friction between the block and wall
`(ii)` The torque by normal reaction about the centre of mass

Explanation

To solve the problem, we will break it down into two parts as requested.

### Part (i): Minimum Coefficient of Friction

1. **Identify the forces acting on the block**:
- The gravitational force \( F_g = mg \) acting downward.
- The applied force \( F \) acting horizontally towards the wall.
- The normal force \( N \) acting perpendicular to the wall.
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