Answer:
-1.94 * 10^-18 J
Since the electron moved from a higher to a lower energy level (n = 3 → n = 1) it is an emission.
Step-by-step explanation:
From Rydberg equation;
E = -RH(1/n^2final - 1/n^2initial)
For a transition from n = 3 → n = 1
RH = 2.18 * 10^-18 J
E = -(2.18 * 10^-18) (1/1^2 - (1/3^2)
E = -(2.18 * 10^-18) (1-1/9)
E= -(2.18 * 10^-18) (8/9)
E = -1.94 * 10^-18 J