The counting rate observed from a radioactive source at t - 0s was 1600 count/s and at t - 8s it was 100 counts/s. The counting rate observed as counts per second at t = 6 s, will be:

Options

A. 400
B. 300
C. 250
D. 150

Answer

D

Explanation

The half -life of source ` = (8)/(4) = 2 s `
Now , `" " R= R_0 ((1)/(2)) ^(n)`
` " " R = 1600 ((1)/(2)) ^((6)/(2))`
` " " = 1600 ((1)/(2))^(3)`
` " " =200`