Where can quarks as a subatomic particle be found? in the electrons?

Answer 1

Electrons have no constituents. They are thought to be fundamental (or "elementary") particles.

Quarks are also thought to be fundamental particles. They are an important constituent of protons and neutrons.

More generally, quarks can be components of many other hadrons; however, these other particles that are traditionally only found in high energy environments, like particle colliders. Quarks are never found alone, except for the top quark which decays too quickly to "hadronize."

Of course, quarks are not the only things that make up these hadrons. Typically these quarks will be combined with other particles and together the collection will make up a particle like a proton, a neutron, or one of the many other hadrons.

Again, I stress that electrons are on par with quarks. Quarks are elementary particles just as are electrons. Electrons are not "made" of quarks. In fact, roughly speaking, electrons can be constituents of other particles just like quarks can.

Answer 2

Quarks are in the protons and neutrons.

Answer 3

I'm pretty sure they are bigger than electrons.