Question

Electronic transition from 4s to 3s orbital is forbidden meaning that it cannot occur because :

• A. there will be no change in the orbital angular momentum of electron, although the emitted photon has angular momentum
• B. there will be change in the orbital angular momentum whereas the emitted photon has no momentum
• C. $\Delta$m${}_1$ values between 4s and 3s is not zero, which is an important selection rule for allowed transition
• D. in 4s and 3s orbitals, the wavelength of the electron wave are the same

Answer 1

The correct option is A there will be no change in the orbital angular momentum of electron, although the emitted photon has angular momentum

Electronic transition from 4s to 3s orbital is forbidden meaning that it cannot occur because there will be no change in the orbital angular momentum of electron, although the emitted photon has angular momentum.
Transition from one energy level to other energy level is allowed when there is change in the angular momentum by 1 unit.
This change in angular momentum is carried away by photon.