Q.
The count rate for 10g of radioactive material was measured at different times and this has been shown in figure with scale given. The half-life of the material and the total count in the first half value period, respectively are
A) 4 h and 9000 (approximately)
B) 3 h and 14100 (approximately)
C) 3 h and 235 (approximately)
D) 10 h and 157 (approximately)
Explanation
(b) Taking average count per minute in the first half value period as (100+50)/2 $ie$, 75
Total number of counts during this period $= 75 \times 3 \times 60 = 13500$ which is closest to the given result (14100)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.