The half-life of 1 g of radioactive sample is 9 hour. The radioactive decay obeys first order kinetics. The time required for the original sample to reduce to 0.2 g is

Options

A. 15.6 hours
B. 156 hours
C. 20.9 hours
D. 2.09 hours

Answer

C

Explanation

`(0.693)/(9) = (2.303)/(t) "log" (1)/(1 - 0.2)`