UPSC Prelims 2009 · General Studies
Question 44: Science and Technology
Who of the following scientists proved that the stars with mass less than 1·44 times the mass of the Sun end up as White Dwarfs when they die ?
AnswerThe answer is (b).
Subrahmanyan Chandrasekhar showed in 1930 that a star left with mass below about 1.44 times the Sun's mass can settle as a white dwarf, supported by electron degeneracy pressure; above that value it collapses further into a neutron star or black hole. This is the Chandrasekhar limit, and he shared the 1983 Nobel Prize in Physics. Hubble showed the Universe is expanding, Hawking worked on black holes and Weinberg on the electroweak theory.
Why each option is right or wrong
- (a) Edwin Hubble showed galaxies are receding, giving evidence of an expanding universe.
- (b) Right: S. Chandrasekhar derived the 1.44 solar-mass limit for white dwarfs.
- (c) Stephen Hawking is known for black hole radiation and cosmology.
- (d) Steven Weinberg is known for the electroweak theory.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2009, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.