Answer: Protons and neutrons
Explanation: Atomic theory explains that all the matter in the world is made up of small tiny indivisible particles known as Atoms. But later on, it was proved that the atoms are not the indivisible particles as it can be divided into sub atomic particles like electrons, protons .
Modern Atomic Theory states that the atom is like a diffused cloud in which electrons are revolving and surrounding a small dense nucleus in which there are protons and nucleus together known as nucleons.
Thus the particles which are present in nucleus can be identified as Protons and Neutrons.