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Topic Radioactive decay
Asked 3 times in CSE over 30 years (1994–2024), peaking in 2024.
Key insights
- Most tested in CSE — 3 of 3 PYQs
- Most asked in 2024
- Recurs across 3 years (1994–2024)
Across exams
CSE · 3How the concept evolved
Long-running — most appearances (2 of 3) predate 2016, and it still returns.
Related concepts
Ideas UPSC tests alongside this one — keep exploring.
Sample questions
You've seen the pattern — here are a few of the actual PYQs.
CSE2024
With reference to radioisotope thermoelectric generators (RTGs), consider the following statements
- RTGs are miniature fission reactors
- RTGs are used for powering the onboard systems of spacecrafts
- RTGs can use Plutonium-238, which is a by-product of weapons development
Which of the statements given above are correct ?
- A 1 and 2 only
- B 2 and 3 only ✓
- C 1 and 3 only
- D 1, 2 and 3
✓ Correct answer: (B)
Science & Technology › Energy & Nuclear
CSE2001
A radioactive substance has a half-life of four Months. Three fourth of the substance would decay in
- A 3 months
- B 4 months
- C 8 months
- D 12 months
Answer key not yet available (pending official release)
Science & Technology › Energy & Nuclear
CSE1994
The half-life of a radio active element is 5 years. The fraction of the radioactive substance that remains after 20 years
- A 1/2
- B 1/4
- C 1/8
- D 1/16 ✓
✓ Correct answer: (D)
Science & Technology › Energy & Nuclear
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