Answer : The nucleus of an atom contains neutrons and proton subatomic particles.
Explanation :
As we know that an atom is the smallest unit of a matter that consist of three subatomic particles which are electrons, protons and neutrons.
The protons and the neutrons are located inside the nucleus or center of the nucleus where the mass of the an atom is concentrated and the electrons are located around the nucleus.
The protons are positively charged, the electrons are negatively charged and the neutrons are neutral that means it has no charge.
Hence, the nucleus of an atom contains neutrons and proton subatomic particles.