Average Atomic Mass Lab Quiz

What is the definition of average atomic mass?

• The sum of protons and neutrons in an atom

• A weighted average of the atomic masses of all the naturally occurring isotopes of an element

• The difference between the sum of the masses of the particles that make up an atom and an atom’s actual mass

• An analytical instrument used to determine the mass of individual species within a sample

Which of the following statements is true about isotopes?

• All isotopes of a given element have different numbers of protons

• An isotope will have the same atomic number but different atomic mass than that of another isotope of the same element

• Most elements have only one naturally occurring isotope

• Isotopes are written with the symbol followed by the atomic number

What is mass defect?

• The number of protons plus neutrons in the nucleus of an atom

• The difference between the sum of the masses of the particles that make up an atom and an atom’s actual mass

• A weighted average of the atomic masses of all the naturally occurring isotopes of an element

• An analytical instrument used to determine the mass of individual species within a sample

How is the mass number of an atom determined?

• By the number of electrons in the atom

• By the number of protons plus neutrons in the nucleus of an atom

• By the atomic number of the element

• By the average atomic mass of the element

What is the function of a mass spectrometer?

• To measure the average atomic mass of an element

• To determine the mass of individual species within a sample

• To calculate the mass defect of an atom

• To identify the number of isotopes of an element

What is nuclear binding energy?

• The energy required to break apart the nucleus into individual protons and neutrons.

• The energy required to combine protons and neutrons.

• The energy required to ionize an atom.

• The energy required to form a chemical bond.

What is the abbreviation for unified atomic mass unit?

• amu

• u

• g

• kg

How is the weighted average of atomic mass calculated if 90 atoms have a mass of 12.0 u and 10 atoms have a mass of 13.0 u?

• 12.0 u

• 12.1 u

• 12.5 u

• 13.0 u

Isotopes of an element have a different number of...

• Protons

• Neutrons

• Electrons

• Mass

Rubidium has two common isotopes, ⁸⁵Rb and ⁸⁷Rb. If the abundance of ⁸⁵Rb is 72.2% and the abundance of ⁸⁷Rb is 27.8%, what is the average atomic mass of rubidium?

• 85.468 amu

• 37 amu

• 85.6 amu

• 86.4 amu