Circle the odd one.
Nucleus
The explanation for the correct option:
B) Nucleus: The nucleus is present at the center of an atom. Almost all of the mass in an atom is made up of the protons and neutrons in the nucleus with a very small contribution from the orbiting electrons. Neutrons have no charge and protons are positively charged.
The explanation for the incorrect option:
A) Electrons: Electrons are the subatomic particle, which revolves around the nucleus in an atom.
B) Protons: Protons are subatomic particle, which is present in the nucleus.
C) Neutrons: Neutrons are the subatomic particle, which is present in the nucleus.
Thus; option (B) is correct, Nucleus is present at the center of an atom.