An 11.8 eV photon is absorbed by an electron in an atom, causing the electron to be excited from level 1 to level 3. The electron then emits a 4.1 eV photon and shifts to level 2. What photon will be emitted when the electron moves back to level 1

Explanation:

energy absorbed by electron to get excited from level 1 to level 3

= 11.8 eV

energy released by electron when it  goes from level 3 to level 2 = 4.1 eV

energy released when electron goes from level 2 to level 1 = 11.8 - 4.1 = 7.7 eV

photon emitted = 7.7 eV photon .

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