Modern Physics Questions and Answers – Page 5

The correct answer is Option A — Higgs Boson. The Higgs Boson is nicknamed the 'God Particle' because it was theorized to be responsible for giving mass to all other particles. Option B (Neutron): The neutron is a neutral subatomic particle found in the nucleus. It is NOT called the God Particle. Option C (Pion): A pion (pi-meson) is a subatomic particle involved in the nuclear force. Option D (Positron): A positron is the antimatter counterpart of an electron (positive charge).

The electron is the lightest of the three fundamental subatomic particles (electron, proton, neutron). Its mass is approximately 9.1 × 10⁻³¹ kg (more precisely 9.10938 × 10⁻³¹ kg). Option A (9.1 × 10⁻²⁸ kg): This is not the correct value for electron mass. It is 1000 times larger than the actual electron mass. Option B (1.67 × 10⁻²⁷ kg): This is the mass of a PROTON, not an electron. The proton is about 1836 times heavier than the electron. While the exponent (-31) is correct, the coefficient 1.67 belongs to the proton/neutron mass.

Sir Joseph John Thomson discovered cathode rays (electrons) in 1897 through experiments with cathode ray tubes. He proved that cathode rays are streams of negatively charged particles, which are now called electrons. He measured the charge-to-mass ratio (e/m) of electrons and proved they are fundamental subatomic particles. Option A — Ernest Rutherford: Rutherford discovered the nuclear model of the atom (1911) and the proton. He did NOT discover cathode rays or electrons. Option B — Goldstein: Eugen Goldstein discovered canal rays (anode rays / positive rays) in 1886. He discovered proton-like positive particles, NOT electrons or cathode rays. Option D — James Chadwick: Chadwick discovered the neutron in 1932. He had nothing to do with the discovery of cathode rays or electrons.