### All AP Chemistry Resources

## Example Questions

### Example Question #1 : Spectroscopy And Electromagnetic Spectrum

What is the energy of a photon that has a wavelength of 540 nm?

**Possible Answers:**

None of the above

**Correct answer:**

; ;

### Example Question #2 : Spectroscopy And Electromagnetic Spectrum

What transition would emit the longest wavelength of light?

**Possible Answers:**

n = 4 to n = 3

n = 3 to n = 1

Not enough information given

n = 2 to n = 1

n = 4 to n = 1

**Correct answer:**

n = 4 to n = 3

Wavelength is inversely proportional to energy. Since the transition from n=4 to n=3 is the lowest energy transition, it would have the longest wavelength.

### Example Question #3 : Spectroscopy And Electromagnetic Spectrum

What photon wavelength can promote a transition from the n = 1 (ground state) to the n = 3 (excited state)?

**Possible Answers:**

1 m

204 nm

102 nm

408 nm

306 nm

**Correct answer:**

102 nm

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### Example Question #4 : Spectroscopy And Electromagnetic Spectrum

A 3.0 eV light is shined on Gold ( Փ = 5.1 eV), silver (Փ =4.26 eV), Cesium (Փ = 2.1 eV), and Platinum (Փ = 6.35). If Փ is the work function of the metal, what metal would have electrons ejected?

**Possible Answers:**

Au

Pt

Cs

Au, Ag, and Pt

Ag

**Correct answer:**

Cs

The work function is the energy required to remove an electron from a metal. Only Cs metal has a work function less than the energy of the light.

### Example Question #5 : Spectroscopy And Electromagnetic Spectrum

A student has a Blue #1 dye with a molar absorptivity of 1.30 x 10^{5} M^{-1} cm^{-1} at 631 nm. If the student runs this sample through a spectrophotometer and finds it has an absorption of 0.500 what is the dye’s molarity? Assume a path length of 1.0 cm.

**Possible Answers:**

**Correct answer:**

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