An atom (not a hydrogen atom) absorbs a photon whose associated wavelength is 300 nm and then immediately emits photon whose associated wavelength is 640 nm. how much net energy is absorbed by the atom in this process?

The net energy is 2.196 eV

Explanation:

Basically, the energy of an atom increases when it absorbs a photon. In addition, the wavelength of the emitted photon is longer such that the atom absorbed a net energy in the process.

Using:

ΔE = h*c*(1/λ - 1/λ)

where:

ΔE is the net energy in eV (electron-volt). 1 eV is equivalent to 1.602* J.

h = 4.135* eVs

c = 3* m/s

λ = 300 nm = 300* m

λ = 640 nm = 640* m

Thus:

ΔE = 4.135* eVs*3* m/s*()

ΔE = 4.135**3**1.77* eV = 2.196 eV

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e