Dear Student,
The Postulates of bohr atomic model are :
1) electrons revolve round the nucleus only in certain permissible circular orbirts , also called shells.
2)each orbit is associated with a definate energy.
3) the energy of an electron remains constant as long as it revolves in a given orbit.
4)when electron absorbs energy, it jumps from a low -energy level to a high-energy level.
5)but, electron at higher energy level is unstable . so, it jumps from higher energy level to lower energy level and gives out energy
Regards