Question

Which one of the following about atomic structure is FALSE?

• A. The electrons occupy a very large volume compared to the nucleus.
• B. The number of protons and electrons in a neutral atom is the same.
• C. The number of electrons in an atom can be found by subtracting the atomic number of an element from the mass number of an element.
• D. Almost all of the mass of an atom is found in the nucleus.

Answer 1

Answer: (C)

The number of electrons in an atom can be found by subtracting the atomic number of an element from the mass number of an element.

Let us take a look at all the options.

Option A says that electrons occupy a large volume as compared to the nucleus. This is true since we know that the nucleus takes up very little space and that the electron cloud is generally 100,000 times bigger than the nucleus.

Option B says that number of protons and electrons in a neutral atom are same which is true since if there were more protons or more electrons the atom would develop a charge and thus not be neutral.
Option C is also true since electrons have very small mass and therefore most of the mass of the atom is found inside the nucleus.

Option D says that the difference between mass number and atomic number should be equal to the number of protons which is not true since this value gives us the number of neutrons.