Answer
(a) emission of energy.
(b) absorption of energy.
(c) emission of energy.
Work Step by Step
(a) Since the transition is from higher energy principal level to lower energy principal level, the energy is emitted.
(b) Since the transition is from lower energy principal level to higher energy principal level, the energy is absorbed.
(c) Since the transition is from higher energy principal level to lower energy principal level, the energy is emitted.
