A charge q is located at the centre of a cube. The electric flux through any face is

This problem can be solved by symmetry consideration and Gauss law.The total flux passing through the closed cube ϕ=qε0All the six surfaces are symmetrical with respect to charge, hence they will have equal contribution of the flux. So, flux through any one face isϕ'=ϕ6=q6ε0ϕface =q6ε0=4πq64πε0