Question

An atom of lithium contains 3 electrons, 3 protons and 4 neutrons. Its mass number is ______.

Options

• 3

• 4

• 7

• 10

Answer 1

An atom of lithium contains 3 electrons, 3 protons and 4 neutrons. Its mass number is 7.

Explanation:

The mass number of an atom is the total number of protons and neutrons present in its nucleus. In a lithium atom, there are 3 protons and 4 neutrons, so the mass number is 3 + 4 = 7.