# Question fc63c

Sep 29, 2017

$\text{B " -> " C}$

#### Explanation:

The idea here is that when an electron makes a transition from an energy level to another, the difference in energy between the two levels will be equal to the energy of the photon emitted or absorbed by the electron.

In your case, the two electrons emit photons when making the transitions, so right from the start, you can say that energy level $\text{B}$ is higher in energy than both energy level $\text{C}$ and energy level $\text{A}$.

Now, the energies of the photons emitted during the transitions are directly proportional to the frequencies of the photons, which, in turn, are inversely proportional to their wavelengths.

Now, you know by looking at the visible portion of the EM spectrum that you have

"B " -> " C" : " "color(blue)("blue light") implies {(ul("high frequency")), ("short wavelength") :} => ul("higher energy photon")

"B " -> " A": " "color(red)("red light") implies {(ul("low frequency")), ("long wavelength") :} implies ul("lower energy photon")#

For electron $\text{X}$, the transition releases blue light, which is higher in frequency than red light. This implies that the energy of the photon emitted when electron $\text{X}$ falls from energy level $\text{B}$ to energy level $\text{C}$ is higher than the energy of the photon emitted when electron $\text{Y}$ falls from energy level $\text{B}$ to energy level $\text{A}$.

Consequently, you can say that the difference in energy between energy level $\text{B}$ and energy level $\text{C}$ is higher than the difference in energy between energy level $\text{B}$ and energy level $\text{A}$.

You can thus say that for electron $\text{X}$, light of higher frequency corresponds to

$\text{B " stackrel(color(white)(aaaaaaaaaaacolor(blue)("higher energy photon")aaaaaaaaaaaaaa))(color(blue)(->)) " C}$

For electron $\text{Y}$, light of lower frequency corresponds to

$\text{B " stackrel(color(white)(aaacolor(red)("lower energy photon")aaaaaa))(color(red)(->)) " A}$