The half life of a radioactive element is 30 min. One sixteenth of the original quantity of element will be left after
a. 1 hr b. 16 hr c. 4 hr d. 2 hr

Options

A. 60 minutes
B. 120 minutes
C. 70 minutes
D. 75 minutes

Answer

B

Explanation

`(1)/(16) =(1)/(2^(n)) or (1)/(2^(4)) = (1)/(2^(n)) or n = 4`
`:.` Required times `= 4xx t_(1//2) = 120` min