The proton was discovered through experiments on
- A. cathode rays
- B. positive rays produced in a discharge tube with a perforated cathode
- C. radioactive decay of uranium
- D. the photoelectric effect
Explanation
Goldstein observed rays travelling towards the cathode and passing through holes in it, and the lightest positive particles, obtained when hydrogen filled the tube, were identified as protons. Cathode rays led to the electron instead, which is the pairing this question tests. The charge to mass ratio of these positive rays depended on the gas used, unlike that of cathode rays.