Mass Spectra of Elements (College Board AP® Chemistry)

Exam Questions

3 mins3 questions
11 mark
mass spectrum for AP chemistry

The mass spectrum of element X is shown above? Which of the following is true?

  • Element X is germanium.

  • X has a relative atomic mass between 71 and 72.

  • The most abundant isotope of X contains a total of 71 protons and neutrons.

  • The spectrum shows the abundance of the isotope 72X is greater than the abundance of the 70X.

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21 mark

Element Z has three isotopes: 70Z, 72Z and 74Z. They occur naturally with abundances of 24.4%, 32.4% and 43.2%, respectively. What is the average atomic mass of element Z?

  • 72.38 amu

  • 72.00 amu

  • 72.22 amu

  • 72.16 amu

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31 mark

A sample of neon contains the isotopes 20Ne and 21Ne. The average atomic mass of the neon sample is 20.2. What is the percentage of 21Ne atoms in the sample of neon?

  • 8.0%

  • 20%

  • 80%

  • 92%

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