Question

The simple Bohr model is not applicable to $H{e}^4$ atom because

• A. electrons are not subject to central forces.
• B. $H{e}^4$ has one more electron.
  
• C. $H{e}^4$ is an inert gas.
  
• D. $H{e}^4$ has neutrons in the nucleus
  

Answer 1

Answer: (A), (B)

$H{e}^4$ has one more electron.


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.:$H,H+,Li+2,Na+1$ etc. So when we look carefully at $H{e}^4$, then it has one more electron i.e., total $2$ electrons. That is not possible in Bohr model. And electrons are not subjected to central forces.

$\text{Final Answer}:$ (c), (d)