# Lesson Worksheet: Emission and Absorption Spectra Physics • 9th Grade

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 absorption spectrum of hydrogen. The absorption line marked A 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 one decimal place.

• A0.5 nm
• B0.8 nm
• C0.7 nm
• D0.1 nm
• E0.4 nm

Q7:

The figure shows part of the emission spectrum of hydrogen. The emission line marked A 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 one decimal place.

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

Q9:

An astronomer looks at the spectrum of light from a distant star. The spectrum he sees is shown in the figure. He compares the emission lines within the spectrum to the emission lines in the spectra of pure elements, which are also shown in the figure, in order to identify which elements are present in the outer layers of the star. State all of the elements that are present in the outer layers of the star.

• AHydrogen and helium
• BHydrogen, helium, boron, and carbon
• CHydrogen, helium, and carbon
• DHydrogen, helium, and boron
• EHelium and carbon

Q10:

A scientist has a gas canister that contains a mixture of unknown gases. In order to identify which gases are in the mixture, 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 several pure, gaseous elements. Which of the five elements does the mixture contain?

• AHydrogen, helium, and nitrogen
• BHydrogen and argon
• CHelium, hydrogen, oxygen, nitrogen, and argon
• DOxygen, helium, and hydrogen
• EHelium, oxygen, nitrogen, and argon