Q1. Consider the following statements regarding global space activity in 2025:
- More than 300 successful space launches were conducted globally.
- The number of objects re-entering Earth’s atmosphere exceeded the number of objects placed in orbit.
- Net growth of objects in orbit was positive despite re-entries.
Which of the statements given above is/are correct?
(a) Only One
(b) Only Two
(c) Only Three
(d) None
Answer: (b) Only Two
Explanation:
- Statement 1 – Correct: ISSAR 2025 reports 315 successful launches, indicating rapid commercialisation and militarisation of space.
- Statement 2 – Incorrect: Objects placed (~4,651) far exceed re-entries (~1,911), showing accumulation rather than depletion.
- Statement 3 – Correct: Despite re-entries, net orbital population increased (~74.5%), highlighting worsening space congestion.
Q2. Consider the following statements:
- In PHWRs, natural uranium is used as fuel.
- In FBRs, depleted uranium is used only as coolant.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (a) 1 only
Explanation:
- Statement 1 – Correct: PHWRs use natural uranium (U-235) with heavy water moderator, making them suitable for India’s limited enrichment capacity.
- Statement 2 – Incorrect:
- Depleted uranium is used as a “blanket” material, not coolant.
- It absorbs neutrons and converts into plutonium (fuel breeding).
- Coolant in FBR → liquid sodium, not uranium.
Q3. Consider the following statements:
Assertion (A): The stepped reservoir at Elephanta Island indicates advanced water management practices.
Reason (R): The island’s rocky terrain leads to low groundwater retention despite high rainfall.
(a) Both A and R are correct and R is the correct explanation of A
(b) Both A and R are correct but R is not the correct explanation of A
(c) A is correct but R is incorrect
(d) A is incorrect but R is correct
Answer: (a)
Explanation:
- Assertion – Correct: The reservoir shows planned hydraulic engineering, not random water storage.
- Reason – Correct: Rocky terrain causes rapid runoff → minimal infiltration, necessitating artificial storage.
- Linkage: The structure was designed precisely to counter this ecological constraint, making R the correct explanation.
Q4. Consider the following statements:
- Pulsars are neutron stars that emit periodic beams of electromagnetic radiation due to their rotation.
- The regularity of pulsar signals allows them to be used as precise cosmic clocks.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (c)
Explanation:
- Statement 1 – Correct: Pulsars are rotating neutron stars emitting beams like a lighthouse effect.
- Statement 2 – Correct: Their extremely stable rotation periods allow precise timing → used in:
- Distance measurement
- Gravitational wave detection
Q5. Consider the following statements regarding the Subansiri Lower Hydroelectric Project:
- It is a run-of-the-river project located on the Assam–Arunachal Pradesh border.
- It is developed by NHPC and has a capacity of 2000 MW.
- All beneficiary states are mandated to procure both firm and unallocated power shares.
- The project faced delays due to environmental concerns and local protests.
Which of the statements given above is/are correct?
(a) 1, 2 and 4 only
(b) 2 and 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4
Answer: (a) 1, 2 and 4 only
Explanation:
- Statement 1 – Correct: It is a run-of-the-river project, though still subject to ecological concerns like hydro-peaking.
- Statement 2 – Correct: Developed by NHPC, capacity 2000 MW (largest hydel project).
- Statement 3 – Incorrect:
- States must accept firm allocation
- But can refuse unallocated central pool (as Assam, Meghalaya did)
- Statement 4 – Correct: Delays due to protests, environmental concerns, dam safety issues, litigation (2011–2019)
