Same chapter1 markDifficulty: Medium
When a nucleus emits a beta particle, its atomic number:
Radioactivity
3 marksDifficulty: Medium
The half-life of a radioactive substance is 5 years. What fraction of an initial sample remains undecayed after 20 years?
Original Khojo Papers practice question — not from a past board paper.
Answer
One sixteenth
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
Twenty years is four half-lives, and each half-life halves the amount remaining, so the fraction left is (1/2)4 = 1/16.
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