why an electron revolve round nucleas,but why it dont get attracted towards the protonsin general negative and positive get attracted

The force b/w them is attractive & electron is actually attracted towards nucleus but it doesn't move towards nucleus since it is having some speed , so the force changes it's direction continuously ( centripital force ) . But if electron would have been at rest  it would have moved towards nucleus .

just imagine, if all the electrons of an atom gets attracted towards the nucleus there will be mutual repulsion between each other and they will be again pushed back towards their original orbit