Q110. Consider the following statements about private entities in India’s space programme:
1. IN-SPACe is an autonomous agency facilitating private participation.
2. Agnikul Cosmos launched the world’s first flight using a 3D-printed rocket engine.
3. Skyroot Aerospace developed liquid fuel for GSLV.
Which statements are correct?
[UPSC CSE Prelims 2026]
(A) 1 only
(B) 2 and 3 only
(C) 1 and 2 only
(D) 1, 2 and 3
Answer: (C) 1 and 2 only
Explanation: IN-SPACe enables private participation in India’s space sector, while Agnikul demonstrated a flight using its additively manufactured engine. Skyroot develops independent launch vehicles; it did not develop GSLV’s liquid propellant. Therefore, the first two statements alone are correct.
Q109. Which of the following pairs of theories about the origin of Earth and their proponents is/are correctly matched?
1. Gaseous Hypothesis — Kant
2. Binary Star Hypothesis — Russell
3. Planetesimal Hypothesis — Chamberlin
[UPSC CDS (I) 2026 – General Knowledge]
(A) 1 only
(B) 2 and 3 only
(C) 1 and 3 only
(D) 1, 2 and 3
Answer: (D) 1, 2 and 3
Explanation: Immanuel Kant proposed an early gaseous nebular explanation, Russell is associated with the binary-star hypothesis, and Chamberlin with the planetesimal hypothesis. These are historical explanations developed before modern observations strengthened the solar nebular model.
Q108. Why is the Earth slightly flattened at the poles and bulged at the equator?
[UPSC NDA (II) 2026 – General Ability Test]
(A) Large oceans in the Southern Hemisphere
(B) The Earth’s rotational force
(C) The Earth’s revolution
(D) Greater gravitational force at the equator
Answer: (B) The Earth’s rotational force
Explanation: The rotation of Earth produces an outward centrifugal effect strongest at the equator and absent at the poles. Over geological timescales this contributes to an oblate spheroidal shape, with a larger equatorial radius than polar radius.
Q107. What is the acceleration due to gravity on a planet having twice Earth’s mass and twice Earth’s radius, if Earth’s value is g?
[RRB Group D, 3 February 2026, Shift 2]
(A) 2g
(B) g/4
(C) g
(D) g/2
Answer: (D) g/2
Explanation: Surface gravity is proportional to mass divided by the square of radius: g = GM/R². Doubling mass multiplies gravity by two, but doubling radius divides it by four. The combined factor becomes one-half.
Q106. Consider these statements:
I. The Prime Meridian and International Date Line are the same.
II. The region west of the International Date Line is generally one calendar day ahead of the east.
III. Earth rotates through 15° longitude per hour.
Which are correct?
[UPSC NDA (II) 2026 – General Ability Test]
(A) I and II only
(B) I and III only
(C) II and III only
(D) III only
Answer: (C) II and III only
Explanation: The Prime Meridian is approximately 0° longitude, while the International Date Line follows approximately 180°. Earth completes roughly 360° in 24 hours, or 15° per hour. Crossing the Date Line changes the calendar date.
Q105. Which planet has the highest density among Mercury, Venus, Jupiter and Earth?
[UPSC NDA (I) 2026 – General Ability Test]
(A) Mercury
(B) Venus
(C) Jupiter
(D) Earth
Answer: (D) Earth
Explanation: Earth has a mean density of approximately 5.51 grams per cubic centimetre, slightly exceeding Mercury and Venus. Jupiter is much less dense because it consists mainly of hydrogen and helium, despite being far more massive.
Q104. Consider the space missions
I. Axiom-4
II. SpaDeX
III. Gaganyaan.
How many of these missions encourage and support microgravity research?
[UPSC CSE Prelims 2025]
(A) Only one
(B) Only two
(C) All three
(D) None
Answer: (B) Only two
Explanation: Axiom-4 enables research aboard the International Space Station and Gaganyaan supports experiments during Indian human spaceflight. SpaDeX primarily demonstrates spacecraft rendezvous and docking rather than serving as a dedicated microgravity research mission. The examination key selects two.
Q103. Regarding GPS-Aided GEO Augmented Navigation (GAGAN), consider:
I. It improves navigation accuracy and integrity.
II. It supports more uniform and high-quality air traffic management.
III. Its benefits are limited exclusively to aviation.
Which statements are correct?
[UPSC CSE Prelims 2025]
(A) I, II and III
(B) II and III only
(C) I only
(D) I and II only
Answer: (D) I and II only
Explanation: GAGAN is India’s satellite-based augmentation system, developed by ISRO and the Airports Authority of India. It improves GPS reliability for aviation while having potential applications beyond aircraft, such as maritime navigation. Therefore the exclusivity claim is incorrect.
Q102. Which hypothesis explains the formation of the solar system from a rotating cloud of gas and dust?
[RRB NTPC (UG), 18 August 2025, Shift 1]
(A) Big Bang Theory
(B) Nebular Hypothesis
(C) Continental Drift Theory
(D) Plate Tectonics Theory
Answer: (B) Nebular Hypothesis
Explanation: The nebular hypothesis proposes that a rotating interstellar cloud collapsed under gravity, forming the Sun centrally and a surrounding disc of material. Planets developed by accretion within that disc. The Big Bang addresses the universe’s early expansion, not individual planetary systems.
Q101. What distinguishes ISRO’s Small Satellite Launch Vehicle (SSLV) from PSLV and GSLV?
[SSC CGL Tier I, 24 September 2025, Shift 3]
(A) A hybrid liquid-solid engine
(B) On-demand, low-cost launches of small satellites
(C) Launching only from sea-based platforms
(D) Launching foreign satellites exclusively
Answer: (B) On-demand, low-cost launches of small satellites
Explanation: SSLV is designed to carry relatively small payloads into low Earth orbit with quicker turnaround and streamlined launch operations. PSLV and GSLV are larger vehicles suited to wider payload classes. Responsiveness and lower mission costs are key SSLV objectives.