Why 2d and 2f orbitals are not possible?

The 2d and 2f orbitals are not possible because of the constraints imposed by quantum mechanics and the principal quantum number (n). The principal quantum number n specifies the energy level and size of the orbital, and for any given n, the maximum angular momentum quantum number (l) can only take values from 0 to n-1. Therefore, for n=2, l can only be 0 (s orbital) or 1 (p orbital), making the 2d and 2f orbitals non-existent.