Question

J.J. Thompson is credited with discovering the proton. electron. neutron. nucleus.

Answer 1

he discovered the electron

Answer 2

J.J. Thompson is credited with discovering the electron. Option B is correct.

Sir Joseph John Thomson was an English physicist and Nobel Laureate in Physics. In 1897, J.J. Thomson discovered the electron, (the first subatomic particle to be discovered), by experimenting with a Crookes, or cathode ray, tube. He proved that cathode rays were negatively charged. Moreover, he also studied positively charged particles in neon gas.  

Thomson was awarded the 1906 Nobel Prize in Physics.