Q50. Which radiation listed carries the greatest energy per photon?
[WBCS Executive Preliminary Examination (2022)]
(A) Ultraviolet
(B) Gamma rays
(C) X-rays
(D) Infrared
Answer: (B) Gamma rays
Explanation: Gamma rays generally occupy the highest-energy, shortest-wavelength region among the listed electromagnetic bands. Photon energy follows E = hf, so radiation with greater frequency carries more energy per photon and often shows stronger penetrating ability.
Q49. Which of the listed locations contains an atomic power station?
[SSC CGL Tier-I (12 December 2022, Shift 1)]
(A) Hirakud
(B) Naharkatiya
(C) Kakrapar
(D) Tatipaka
Answer: (C) Kakrapar
Explanation: Kakrapar in Gujarat has a nuclear electricity station using fission reactors. Hirakud is associated with hydropower, while Naharkatiya and Tatipaka are associated with petroleum or natural-gas installations rather than nuclear generation.
Q48. If alpha, beta and gamma radiations have the same momentum magnitude, how do their associated wavelengths compare?
[SSC CGL memory-based test (2 December 2022, Shift 1)]
(A) Alpha has the greatest
(B) Beta has the greatest
(C) Gamma has the greatest
(D) All wavelengths are equal
Answer: (D) All wavelengths are equal
Explanation: For equal momentum p, the associated wavelength is λ = h/p. Thus the numerical wavelengths are identical. Alpha and beta are matter particles, whereas gamma radiation consists of photons, but the momentum-wavelength relation still applies.
Q47. Which is the radioactive isotope of hydrogen?
[SSC CPO Tier-I (10 November 2022, Shift 2)]
(A) Xenon
(B) Technetium
(C) Thorium
(D) Tritium
Answer: (D) Tritium
Explanation: Tritium, or hydrogen-3, has one proton and two neutrons. It undergoes beta-minus decay and is used as a tracer and in fusion research. Ordinary protium and stable deuterium do not undergo spontaneous radioactive decay.
Q46. Who collaborated with Ernest Lawrence in developing the cyclotron?
[SSC CPO Tier-I (9 November 2022, Shift 3)]
(A) J. J. Thomson
(B) Ernest Rutherford
(C) M. S. Livingston
(D) Enrico Fermi
Answer: (C) M. S. Livingston
Explanation: Milton Stanley Livingston worked with Ernest O. Lawrence on early cyclotron development. The device accelerates charged particles by combining an oscillating electric field with a magnetic field, enabling experimental studies of atomic nuclei.
Q45. Which was India’s first operating nuclear electricity station?
[RRB Group D (18 August 2022, memory-based)]
(A) Tarapur
(B) Narora
(C) Rajasthan Atomic Power Station
(D) Kalpakkam
Answer: (A) Tarapur
Explanation: Tarapur Atomic Power Station in Maharashtra began commercial nuclear electricity generation in 1969 and is recognised as India’s first nuclear power station. Narora, Rawatbhata and Kalpakkam began operations later.
Q44. Assess these statements:
(1) Radioactivity is a property of atomic nuclei.
(2) A hydrogen bomb relies principally on nuclear fission.
Which is correct?
[UPPCS Preliminary Examination (2021)]
(A) Statement 1 only
(B) Statement 2 only
(C) Both statements
(D) Neither statement
Answer: (A) Statement 1 only
Explanation: Radioactive emissions originate in unstable nuclei, so radioactivity is a nuclear property. A hydrogen bomb is thermonuclear and derives major energy from nuclear fusion, even though fission is generally used to initiate it.
Q43. Which option links the origin of nuclear energy with the physicist who expressed mass–energy equivalence?
[UPSC NDA-II General Ability Test (14 November 2021)]
(A) Nuclear fission — Einstein
(B) Nuclear fission — Rutherford
(C) Nuclear fusion — Bohr
(D) Nuclear fusion — Heisenberg
Answer: (A) Nuclear fission — Einstein
Explanation: The intended pairing is nuclear fission with Einstein’s mass–energy equivalence. Nuclear energy may arise from either fission or fusion, and Einstein’s E = mc² explains how a small mass deficit can yield substantial released energy.
Q42. Regarding fission:
(1) It can describe cell division in some unicellular organisms.
(2) It converts heavy nuclei into smaller nuclei.
(3) It creates heavy nuclei by combining smaller nuclei.
Which are correct?
[UPSC CDS-I General Knowledge (2021)]
(A) 1 only
(B) 2 only
(C) 1 and 2 only
(D) 1 and 3 only
Answer: (C) 1 and 2 only
Explanation: The term fission is used in biology for a form of cell division and in physics for splitting heavy nuclei. Combining light nuclei instead describes nuclear fusion. Consequently, statements one and two apply, while statement three does not.
Q41. What is the SI unit used for radioactive activity?
[RRB NTPC CBT-I (13 March 2021, Shift 2)]
(A) Faraday
(B) Becquerel
(C) Rutherford
(D) Curie
Answer: (B) Becquerel
Explanation: One becquerel represents one nuclear disintegration per second. The curie is an older, much larger non-SI activity unit equal to 3.7 × 10¹⁰ becquerels. Radioactive activity describes decay rate, not energy absorbed by tissue.
