Worksheet: Units of Nuclear Physics: the Unified Atomic Mass Unit

In this worksheet, we will practice converting between kilograms and unified atomic mass units.

Q1:

The mass of one atom of potassium-40 is 39.9640 u. What is the molar mass of potassium-40 in grams per mole?

  • A 39,964.0 g/mol
  • B 39.9640 g/mol
  • C 0.0399640 g/mol
  • D 39,964,000 g/mol
  • E 3.99640 g/mol

Q2:

What is 6 . 4 7 × 1 0 kg in unified atomic mass units? Give your answer to 3 significant figures.

  • A 6.47 u
  • B 0.0257 u
  • C 3.90 u
  • D 25.7 u
  • E 39.0 u

Q3:

What is 3 u in kilograms? Give your answer to 3 significant figures.

  • A 1 . 6 6 × 1 0 kg
  • B 1 . 4 9 × 1 0 kg
  • C 4 . 9 8 × 1 0 kg
  • D 1 . 4 9 × 1 0 kg
  • E 4 . 9 8 × 1 0 kg

Q4:

A platinum-194 atom has a mass of 193.963 u. What is the mass of a platinum-194 atom in kilograms? Give your answer to 6 significant figures.

  • A 3 . 2 2 0 8 3 × 1 0 kg
  • B 1 . 9 3 9 6 3 × 1 0 kg
  • C 3 . 2 2 0 8 3 × 1 0 kg
  • D 1 . 6 6 0 5 4 × 1 0 kg
  • E 1 . 9 3 9 6 3 × 1 0 kg

Q5:

Uranium-238 has a molar mass of 238.051 g/mol. What is the mass of one atom of uranium-238 in unified atomic mass units?

  • A 238.000 u
  • B 2.38051 u
  • C 238,051 u
  • D 238.051 u
  • E 0.238051 u

Q6:

What is 12.0 µg in unified atomic mass units? Give your answer to 3 significant figures.

  • A 1 . 2 0 × 1 0 u
  • B 1 . 3 8 × 1 0 u
  • C 1 . 3 8 × 1 0 u
  • D 7 . 2 3 × 1 0 u
  • E 7 . 2 3 × 1 0 u

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