Which of these electron transitions correspond to absorption of energy and which to emission?

a) n = 2 to n = 4,

b) n = 3 to n = 1,

c) n = 5 to n = 2,

d) n = 3 to n = 4.

Which of these electron transitions correspond to absorption of energy and which to emission?

a) n = 2 to n = 4,

b) n = 3 to n = 1,

c) n = 5 to n = 2,

d) n = 3 to n = 4.