what is the maximum number of electrons which can be accommodated in an atom in which the highest principal quantum number values is 4?

The orbitals in the fourth shell will be : 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶. The maximum number of electrons can be found when all the orbitals are completely filled. So in this case, the maximum number of electrons will be 36. Also, we can find the maximum number of electrons in a shell with the help of following formula:

Maximum number of electrons = 2n² where n, is the principal quantum number.