Correct Option (D)
All four statements regarding neutrinos are correct.
- Statement 1: Neutrinos are fundamental elementary particles that possess no electric charge, making them electrically neutral. They are observed to travel at speeds extremely close to the speed of light.
- Statement 2: Neutrinos are indeed created in various nuclear processes, prominently during beta decay. In this type of nuclear reaction, a neutron transforms into a proton, an electron, and an electron antineutrino, or a proton transforms into a neutron, a positron, and an electron neutrino.
- Statement 3: While initially theorized to be massless, experimental evidence from neutrino oscillation experiments (e.g., Super-Kamiokande) has conclusively demonstrated that neutrinos possess a very small, but non-zero mass. This discovery was a significant advancement in particle physics.
- Statement 4: Due to their extremely weak interaction with other matter (they interact only via the weak nuclear force and gravity), neutrinos can pass through vast amounts of material, including the Earth and human bodies, almost entirely unimpeded. Trillions of neutrinos, primarily originating from the Sun, pass through our bodies every second without being detected by ordinary means.
Incorrect Options
Options (A), (B), and (C) are incorrect because they exclude one or more statements that are factually accurate descriptions of neutrinos. Since all four statements (1, 2, 3, and 4) correctly describe properties and behaviour of neutrinos, option (D) is the only choice that encompasses all true statements.