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A radioactive substance of mass 768g has a half life of 3 years. After how...

Physics
WAEC 2006
A radioactive substance of mass 768g has a half life of 3 years. After how many years does this substance leave only 6g undecayed?
  • A. 21
  • B. 18
  • C. 15
  • D. 12
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Correct Answer: Option A
Explanation
\(768 \to 384 \to 192 \to 96 \to 48 \to 24 \to 12 \to 6\)

7 x 3 = 21yrs
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Project Topics and Materials, Post-UTME past questions - Download now or upload yours to get paid
Join your school's WhatsApp group
NECO June/July 2024 - Get offline past questions & answers - Download objective & theory, all in one app 48789
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
Project Topics and Materials, Post-UTME past questions - Download now or upload yours to get paid
Join your school's WhatsApp group
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
NECO June/July 2024 - Get offline past questions & answers - Download objective & theory, all in one app 48789