# Worksheet: Emission and Absorption Spectra

In this worksheet, we will practice determining the composition of a material from the features that appear in the spectrum of light coming from it.

Q1:

A scientist has a sample of an unknown gas. In order to identify it, she shines a continuous spectrum of white light through the gas and observes which wavelengths of light are absorbed by it. This is shown in the figure, as well as the absorption spectra of five pure, gaseous elements. Which of the five elements is the unknown gas? • AOxygen
• BArgon
• CXenon
• DHelium
• ENeon

Q2:

A scientist has a sample of an unknown gas. In order to identify the gas, he looks at the spectrum of visible light emitted from it when it is heated. This is shown in the figure. Also shown in the figure are the emission spectra of five pure, gaseous elements. Which of the five elements is the unknown gas? • AXenon
• BArgon
• COxygen
• DHelium
• ENeon

Q3:

A scientist has a sample of an unknown gas. In order to identify the gas, she looks at the spectrum of visible light emitted from it when it is heated. This is shown in the figure. Also shown in the figure are the emission spectra of three pure, gaseous elements. Which of the three elements is the unknown gas? • AHelium
• BHydrogen
• COxygen

Q4:

The figure shows the absorption spectrum for xenon between 400 nm and 420 nm. Which of the absorption lines marked on the diagram has the greatest width? • ALine A
• BLine E
• CLine D
• DLine F
• ELine B

Q5:

The figure shows the emission spectrum for xenon between 540 nm and 550 nm. Which of the emission lines marked on the diagram has the greatest width? • ALine F
• BLine C
• CLine B
• DLine A
• ELine G

Q6:

The figure shows part of the emission spectrum of hydrogen. The emission line marked is the 656.3 nm emission line in the Balmer series. What is the width of the emission line from the point where the intensity is 0 on one side of the line to where the intensity is 0 on the other side? Give your answer to 1 significant figure. Q7:

The figure shows part of the absorption spectrum of hydrogen. The absorption line marked is the 410.2 nm emission line in the Balmer series. Which of the following is the width of the emission line from the point where the intensity is 0 on one side of the line to where the intensity is 0 on the other side? Give your answer to 1 significant figure. • A0.5 nm
• B0.8 nm
• C0.7 nm
• D0.1 nm
• E0.4 nm

Q8:

An astronomer looks at the spectrum of light from a distant star. Between Earth and the star is a large cloud of dust and gas. The star emits continuous-spectrum white light, but some of the light is absorbed by the cloud. The figure shows the spectrum of light that the astronomer observes as well as the absorption spectra of several pure elements. Which of the five elements shown does the interstellar cloud contain? • AHydrogen and helium
• BHydrogen and oxygen
• COxygen and nitrogen
• DOxygen and carbon
• EHydrogen, helium, and nitrogen