In the quantum world of atoms, the spatial existence of electrons around nucleus is uncertainly defined. It turns out that the probability of the spatial distribution of electron around the nucleus is far more complex than simpler orbital revolution. So when it is asked if the electron revolves in a particular orbit the correct answer should be 'we do not know, it's a probabilistic world down there'. When it is just asked if the electron revolves, the correct answer is 'could be but not necessarily'.......... an easy explanation would be that according to the classical physics of the time, if an electrical charge is accelerating (as anything spinning around in an orbit does), then it must radiate energy (as light). A calculation shows that in that case, the electrons would spiral into the nucleus within a tiny fraction of a second.But easily for this standard we could probably ignore this due to the presence of centrifugal force which cross out the electrostatic force.And as u know the Heisenberg Uncertainty Principle..We cant rreally know the position of an electron in an Atom.So the bottom line is that if you really look at it..You dont know whats happening to the electron.So you cant really find out the answer..