Here are the energy levels in a fantasy hypothetical hydrogen-like atom. (You cannot use the Rydberg constant, 2.18 x 10-18 J, for this problem, therefore). What is the frequency of a photon that is absorbed when an electron goes from level 2 to level 4? Energyn = 4 -2.10 x 10-19 Jn = 3 -3.20 x 10-19 Jn = 2 - 5.20 x 10-19 Jn = 1 - 9.80 x 10-19 J

4.7 x 10^14 Hz

Explanation:

From Bohr's theory, the energy absorbed or emitted (ΔE) by an atom transiting from one energy level to another is given as;

ΔE = E4 - E2

Where;

E4 = energy corresponding to the energy level n=4

E2 = energy corresponding to the level n= 2

ΔE = (-2.10 x 10-19) - ( - 5.20 x 10-19)

ΔE =3.1 x 10-19

But

ΔE = hf

h = Plank's constant

f= frequency of photon absorbed

f = ΔE/h = 3.1 x 10-19/6.6 x 10-34

f = 4.7 x 10^14 Hz

the correct answer would be d. hope this !