Question

A point charge q is placed at the corner of a cube

Answer 1

the charge is placed at the corner of the cube.

Now let us add 7 more similar cubes to this cube to make it a larger cube

now this larger cube is composed of 8 cubes with the charge q at its center.

Net flux=Φ

Φ=q/ε

Φ is for 8 cubes

therefore flux for single cube is

Φ'=Φ/8

=q/8ε

now Φ' is for a single cube.

Therefore flux for a side of the cube will be

Φ'/3   (as only through 3 sides the flux passes)

=Φ/24

=q/24ε

hope this helps.