Atomic Mass and Isotopes Quiz

Why do chemists prefer using a standard atom like carbon-12 for atomic mass comparisons?

• Because it is the lightest element.

• Because subatomic particles have very small masses.

• Because subatomic particles have very large masses.

• Because it is the heaviest element.

What is the mass of carbon-12 in unified atomic mass units?

• 12 u

• 4 u

• 16 u

• 1 u

Why does the periodic table not show exactly 12 for carbon's atomic mass?

• Because carbon is not a stable element.

• Because carbon is the lightest element.

• Because there are multiple isotopes of carbon.

• Because carbon is the heaviest element.

Which isotope of carbon is radioactive?

• Carbon-14

• Carbon-15

• Carbon-13

• Carbon-12

What is the approximate average atomic mass of carbon?

• 13.01 u

• 12.01 u

• 15.01 u

• 14.01 u

How is the average atomic mass of an element calculated?

• By adding the masses of all isotopes.

• By multiplying the masses of all isotopes.

• By dividing the mass of the heaviest isotope by the lightest.

• By taking a weighted average based on natural abundances.

What is the most common isotope of oxygen?

• Oxygen-16

• Oxygen-18

• Oxygen-17

• Oxygen-19

What is the approximate average atomic mass of oxygen?

• 15.00 u

• 16.00 u

• 17.00 u

• 18.00 u

Which of the following isotopes of oxygen has the smallest natural abundance?

• Oxygen-16

• Oxygen-19

• Oxygen-18

• Oxygen-17

Why is the average atomic mass of oxygen close to 16u?

• Because oxygen-17 is the most common isotope.

• Because oxygen-16 is the least common isotope.

• Because oxygen-16 is the most common isotope.

• Because oxygen-18 is the most common isotope.