The half-life of a radioactive substance is 20 minutes. The approximate time interval \[\left( {{t}_{2}}-{{t}_{1}} \right)\] between the time \[{{t}_{2}}\] when \[\frac{2}{3}\] of it has decayed and time \[{{t}_{1}}\] when \[\frac{1}{3}\] of it had decayed is-
A)7 min
B)14 min
C)20 min
D)28 min
Correct Answer:
C
Solution :
Time equal to half life spends in decaying substance to half of present value.