The simple Bohr model is not applicable to He4 atom because

The simple Bohr model is not applicable to He4 atom because(a) He4 is an inert gas (b) He4 has neutrons in the nucleus(c) He4 has one more electron(d) electrons are not subject to central forces

(c, d),Key concept: Bohr proposed a model for hydrogen atom which is also applicable for some lighter atoms in which a single electron revolves around a stationary nucleus of positive charge Ze (called hydrogen like atom). It is valid only for one electron atoms, e.g. : H, He,+,, Li,+2,, Na,+1, etc.,The Bohr model is not applicable to He4, as it has one more electron and electrons are not subjected to central forces.