Answer :
The correct energy transition that may take place in the atom if its electron has absorbed a photon is:
OD. n=1 to n=3
Explanation:
1. In an atom, electrons can move to higher energy levels (n values) by absorbing photons.
2. The energy transition from n=1 to n=3 means that the electron moves from the first energy level to the third energy level.
3. This transition corresponds to the electron gaining energy from the absorbed photon and moving to a higher orbit or energy level within the atom.
Therefore, option OD (n=1 to n=3) is the correct answer for the energy transition that may occur in the atom when its electron absorbs a photon.