UPSC Prelims 2001 · General Studies
Question 107: Science and Technology
Match List I with List II and select the correct answer using the codes given below the Lists: List I (Characteristic) I. Zero mass II. Fractional charge III. Fractional spin IV. Integral spin List II (Particle) A) Positron B) Neutrino C) Quark D) Phonon
AnswerThe answer is (a).
The neutrino has zero mass (taken as massless at the time); the quark has a fractional charge (one-third or two-thirds of the electron's); the positron is a fermion with spin one-half, a fractional spin; and the phonon, a quantum of lattice vibration, behaves as a boson with integral spin. Remember that fermions have half-integer spin and bosons have integer spin.
- I. The neutrino has zero mass.
- II. The quark has fractional charge.
- III. The positron has spin one-half, a fractional spin.
- IV. The phonon has integral spin.
Why each option is right or wrong
- (a) Right: neutrino, quark, positron, phonon.
- (b) All four matches are wrong.
- (c) The first two are right, but the last two are swapped.
- (d) The first two are swapped; the last two are right.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2001, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.