Question

Lithium has 3 electrons, 4 neutrons and 3 protons. Its mass number is:

• A. 3
• B. 4
• C. 7
• D. 1

Answer 1

The correct option is C

7

The correct option is (C).

Explanation of correct option:

1. The sum of the number of neutrons and protons in an atom of the element is called a mass number of an atom.
2. Lithium contains 3 electrons, 4 neutrons, and 3 protons.
3. Mass number (A) = Number of Proton + Number of Neutron
4. Mass number (A) = 3 + 4 = 7

Explanation of incorrect option:

Option (A): The number of protons present in the nucleus of an atom of an element is known as its atomic number. So, 3 is the atomic number of lithium.

Option (B): 4 is the neutron present in the Lithium.

Option (D): 1 is not associated with the lithium so this is also an incorrect option.

Thus, Lithium has 3 electrons, 4 neutrons, and 3 protons Its mass number is 7.