The count rate for `10 g` of radioactive material was measured at different times and this has been shown in the above graph with scale given. The half-life of the material and the total count in the first half-value period, respectively are.

Options

A. 4 hours and 9000 (approximately)
B. 3 hours and 14100 (approximately)
C. 3 hours and 235 (approximately)
D. 10 hours and 150 (approximately)

Answer

B

Explanation

(b) Half-value period `= 3 hours`
`= 3 xx 60 minutes = 180 minutes`
Approximate mean disintegration rate
=`(100 + 50)/(2) = 75`
Total count in first half-valur period
=`75 xx 180 ~~ 13500`
Total number of disintegrations is slightly greater than `13500`.