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Knowledge Traditions and Practices of India, Part I

Class 11 · Art & Culture

Ch 5 · Astronomy in India

Real UPSC Prelims questions from 2016–2026, linked to this book. Try each one first, then open the answer. 2026 answers follow UPSC's provisional answer key.

Prelims 2017 · Q87

What is the purpose of 'evolved Laser Interferometer Space Antenna (eLISA)' project?

(a)To detect neutrinos
(b)To detect gravitational waves
(c)To detect the effectiveness of missile defence system
(d)To study the effect of solar flares on our communication systems

Show answer

UPSC's answer: (b)

NCERT answers it: Class 11 Knowledge Traditions and Practices of India, Part I, Ch 5 (Astronomy in India).

How to solve it with NCERT: Class 11 Knowledge Traditions and Practices of India (Part I), ch 5: LIGO, a Laser Interferometer Gravitational-Wave Observatory, detects gravitational waves. eLISA is the same kind of instrument — a laser interferometer — placed in space. Answer (b).

Beyond NCERT: eLISA is now called LISA, a European Space Agency mission planned for launch around 2035. It will be the first gravitational-wave observatory in space. Source: ESA, LISA factsheet, esa.int

Hindi version: UPSC's official question paper (2017), question 87 ↗

Prelims 2019 · Q97

Recently, scientists observed the merger of giant 'blackholes' billions of light-years away from the Earth. What is the significance of this observation?

(a)'Higgs boson particles' were detected.
(b)'Gravitational waves' were detected.
(c)Possibility of inter-galactic space travel through 'wormhole' was confirmed.
(d)It enabled the scientists to understand 'singularity'.

Show answer

UPSC's answer: (b)

NCERT answers it: Class 11 Knowledge Traditions and Practices of India, Part I, Ch 5 (Astronomy in India).

The one fact NCERT doesn't give: The gravitational waves detected in 2015 came from two black holes merging into one, about 1.3 billion years ago.

Class 11 Knowledge Traditions and Practices of India (Part I), ch 5: Indian scientists were part of the team that announced in 2016 the discovery of gravitational waves predicted by Einstein. With the fact, the black-hole merger is that discovery. Answer (b).

Hindi version: UPSC's official question paper (2019), question 97 ↗

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