The Simple Bohr model cannot be directly applied to calculate the energy levels of an atom with many electrons . This is because

Question

$\begin{array}{1 1} \text{of the electrons not being subject to a central force} \\ \text{of the electrons colliding with each other } \\ \text{of screening effect} \\ \text{the force between the nucleus and an electron will no longer be given by coulomb's law} \end{array}$