The length of each side of a cubical closed surface is l. If charge q is situated on one of the vertices of the cube, then the flux passing through each face of the cube will be

The charge contributes only (q/8)th to this cube. Further, these faces of the cube meet at one corner which are parallel to the charge. From Gauss theoremΦone face =(q/8)3ε0=q24ε0