Question

In your textbook, read about mass of individual atoms.

Circle the letter of the choice that best completes the statement.
24. The mass of an electron is
a. smaller than the mass of a proton.
b. smaller than the mass of a neutron.
25. One atomic mass unit is
c. a tiny fraction of the mass of an atom.
d. all of the above.
a. 1/12 the mass of a carbon-12 atom.
b. 1/16 the mass of an oxygen-16 atom.
c. exactly the mass of one proton.
d. approximately the mass of one proton plus one neutron.
26. The atomic mass of an atom is usually not a whole number because it accounts for
a. only the relative abundance of the atom's isotopes.
b. only the mass of each of the atom's isotopes.
c. the mass of the atom's electrons.
d. both the relative abundance and the mass of each of the atom's isotopes.

Answer 1

The mass of an electron is smaller than the mass of a proton. One atomic mass unit is 1/12 the mass of a carbon-12 atom. The atomic mass of an atom is usually not a whole number because it accounts for both the relative abundance and the mass of each of the atom's isotopes.

Step-by-step explanation:

The correct answers for the given statements are:

1. a. smaller than the mass of a proton.
2. a. 1/12 the mass of a carbon-12 atom.
3. d. both the relative abundance and the mass of each of the atom's isotopes.

These answers are supported by the following facts:

• The mass of an electron is significantly smaller than the mass of a proton.
• An atomic mass unit is defined as 1/12 the mass of a carbon-12 atom, which is used as a reference for atomic masses.
• The atomic mass of an atom takes into account both the relative abundance and the mass of each of its isotopes, which can result in a non-whole number value.

Learn more about Atomic structure and atomic mass