Question

1. choose the best answer.

what did j. j. thomson theorize?
cathode rays have a specific mass.
cathode rays are smaller than atoms.
cathode rays are particles.
cathode rays must travel through a vacuum.

Explanation:

J. J. Thomson conducted experiments with cathode rays. He showed that cathode rays are made up of negatively - charged particles (electrons). While other scientists might have made some related observations (e.g., cathode rays can travel through a vacuum was known before in a basic sense of vacuum tubes, but not the particle nature), Thomson's key contribution was theorizing that cathode rays are particles.

Answer:

Cathode rays are particles.