Question

What is the smallest particle even smaller than atom ?

Answer 1

The smallest particle even smaller than atom are Proton, Neutron and electron because they are inside atom

Answer 2

The smallest particle even smaller than an atom are electrons , neutron, protons, neutrino,meson, positron , and many more

And a particle even smaller than protons neutrons is something called as pentaquark

Hope this helped u :-)