After two hours, one-sixteenth of the starting amount if a certain radioactive isotope remained undecayed . The half-life of the isotope is

Options

A. 15 minutes
B. 30 minutes
C. 45 minutes
D. 1 hour

Answer

B

Explanation

(b) `(N)/(N_0) = ((1)/(2))^(t//T) rArr ((1)/(16)) = ((1)/(2))^(2//T) rArr ((1)/(2))^4 = ((1)/(2))^(2//T)`
`rArr T = 0.5 hour = 30` minutes.