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

Half-value period =3hours
=3 x 60 minutes = 180 minutes
Approximate mean disintegration rate
`=(100+50)/2=75` disintegration/minute
`therefore` Total count in first half-value period
`=75xx180 ~= 13500`