Apply Now Student Hub Feedback
UPSC CSE · Prelims · 2013
General Studies (Paper 1) from UPSC CSE 2013 Prelims
Subject: General Studies (Paper 1) Science and Technology Union Public Service Commission — Civil Services Examination Last updated May 9, 2026
UPSC CSE Prelims 2013 General Studies (Paper 1)

Consider the following phenomena:

1. Size of the sun at dusk
2. Colour of the sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky
5. Polestar being visible in the sky 

Which of the above are optical illusions?  

Answer & Explanation

Click "Check Answer" to reveal
Correct Answer: Option A — 1, 2 and 4 only
• Correct Answer: (a) 1, 2 and 4 only
• Explanation: These are caused by atmospheric refraction and scattering. The Moon and Polestar (3 and 5) are physically present in the sky, not illusions created by the atmosphere.
Answer verified by Quintessence Classes faculty — Karan Nagar, Srinagar.

About this question

UPSC CSE 2013 Prelims

Details

Exam UPSC CSE
Stage Prelims
Year 2013
Subject General Studies (Paper 1)
View all questions from this paper

More General Studies (Paper 1) questions

From across UPSC, JKPSC, and JKSSB papers — same subject, different years.

Practice 1,142+ more PYQs interactively

Filter by subject, year, and exam in real time. Get instant feedback, detailed explanations, and track your progress.

Open practice portal