A charge ‘q’ is placed at one corner of a cube as shown in figure. The flux of electrostatic field E→ through the shaded area is:

Imagine 7 more such small cubes and arrange all 8 in such a way that charge q is at the center of big cube.Flux through big cube =Q∈0Thus, flux through small cube =Q8∈0Now , the flux through the 3 adjoining faces to origin of small cube is zero, because field lines does not cross.So, we can say,  flux through 3 opposite faces =Q8∈0  Hence, flux through two half faces = flux through one full face = ϕ=Q24∈0