# General F005: Atomic Mass

All atomic masses in this quiz are based on the standard atomic mass scale, where pure carbon-12 is defined as having an atomic mass of exactly 12 mass units.

The following questions are multiple choice; clearly circle the answer which you think is the most appropriate. These questions are for self-testing only, and are not suitable for assignments or exams.

1. On Earth, the element boron is a mixture of two isotopes, boron-10 and boron-11. Boron-10 has an atomic mass of 10.013 and makes up 19.9% of the total; the remaining 80.1% is boron-11, with an atomic mass of 11.009. What is the standard atomic weight for terrestrial boron?

 A 10.5 B 10.8 C 50.5 D 63.98

2. A mass spectrometer shows that a sample of terrestrial copper contains two isotopes: 63 Cu(69.15%, atomic mass 62.9296) and 65Cu (30.85%, atomic mass 64.9278). What is the atomic weight for this sample of copper?

 A 301.46 B 70 C 63.55 D 65

3. A sample of helium from Jupiter contains 0.022% 3He (atomic mass 3.0160) and 99.978% 4He (atomic mass 4.0026). Calculate the atomic weight for this sample of helium.

 A 3.5066 B 4.0024 C 4.0026 D 3.0106