Sample questions
CDS2025
Twinkling of a star is due to :
- A Interference of light
- B Refraction of light
- C Polarization of light
- D Diffraction of light
Answer key not yet available (pending official release)
Science & Technology › Physics & Chemistry
GEO2025
A glass bar (refractive index = 1·5) is immersed in a liquid having the same refractive index as that of glass. The angle of incidence for a light ray at which the light would be transmitted through the glass bar without reflecting is
- A 30°
- B 45° ✓
- C 60°
- D 75°
✓ Correct answer: (B)
Science & Technology › Physics & Chemistry
CDS2024
The phenomenon of rainbow formation by water droplets involves :
- A single refraction of sunlight
- B one internal reflection of sunlight
- C two internal reflections of sunlight
- D both refraction and internal reflection of sunlight ✓
✓ Correct answer: (D)
Science & Technology › Physics & Chemistry
Study how UPSC repeats — not just the papers
₹199 / 1 year · Founding Member
Full access unlocks the three things no PYQ PDF gives you:
① Cross-exam learning — see the same idea recur across CSE, CAPF, CDS and NDA.
② Topic evolution — how each idea is framed, year by year.
③ Question intelligence — every PYQ + answer, linked to related concepts and similar questions.
e.g. Round Table Conference: CDS 2017 → CSE 2017 → … → CAPF 2024
15 days free, no card required — then ₹199 for 1 year.
Start your 15-day free trial →