CDS (II) 2021 · General Knowledge
A full General Knowledge paper in the UPSC CDS pattern: 120 questions in 2 hours, with a third of the question's marks deducted for every wrong answer. Physics, Chemistry, Biology, defence and security, History, Geography, Polity, Economy and current events.
120questions
100marks
2 hoursno calculator
47/61/12easy / medium / hard
Topics in this paper
General Knowledge · 120 questions
- Current Events6
- Human physiology5
- Sports5
- World Geography5
- Optics4
- Freedom Struggle4
- Indian Geography4
- Awards3
- Modern India3
- Indian Rivers3
- Parliament3
- Sound2
- Everyday chemistry2
- Metals2
Sample question from this paper
Optics · medium
The brilliant sparkle of a diamond is mainly due to
- A. its high density
- B. dispersion alone
- C. total internal reflection of light inside it
- D. scattering of light at its surface
Show answer and solution
Answer: C
Diamond has a very high refractive index of about 2.42, so its critical angle is only about 24 degrees. Light entering it undergoes repeated total internal reflection before emerging, which produces the sparkle. Density has no role, and dispersion only adds colours.
Diamond has a very high refractive index of about 2.42, so its critical angle is only about 24 degrees. Light entering it undergoes repeated total internal reflection before emerging, which produces the sparkle. Density has no role, and dispersion only adds colours.