Question

Which of the following statement is always correct?

• A. An atom has equal number of electrons and protons.
• B. An atom has equal number of electrons and neutrons.
• C. An atom has equal number of protons and neutrons.
• D. An atom has equal number of electrons, protons and neutrons.

Answer 1

The correct option is A

An atom has equal number of electrons and protons.

Explanation for correct option:

Option A: An atom has equal number of electrons and protons:

1. An atom is electrically neutral particle.
2. Thus, atom has equal number of positively charged protons and negatively charged electron.
3. The electrical neutrality of the atom is necessary for its stability.

Example:

1. Consider a Carbon $\mathbf{\left(}\mathbf{C}\mathbf{\right)}$ atom.
2. The Carbon atom has six protons and six electrons.
3. Thus, it has equal number of protons and neutrons and is electrically neutral.

Explanation for incorrect options:

Option B: An atom has equal number of electrons and neutrons:

An atom does not always have equal number of electrons and neutrons.

Option C: An atom has equal number of protons and neutrons:

An atom does not always have equal number of protons and neutrons.

Option D: An atom has equal number of electrons, protons and neutrons:

An atom does not always have equal number of electrons, protons and neutrons.

Thus, Option (A) is the correct option.