The half-life a radioacitve substance is `40` yeard. How long will it take to reduce to one fourth of its original amount and what is the value of decay constant ?

Options

A. `40 years, 0.9173//year`
B. `90 year, 9.017//year`
C. `80 year, 0.0173 year`
D. None of these

Answer

C

Explanation

( c) To reduce one fourth it takes time `t = 2(T_(1//2)) = 2 xx 40`
=`80 years`
Decay constant `lamda = (0.693)/(T_(1//2)) = (0.693)/(40) = 0.0173 years`.