Answer: half life
Explanation: Radioactive decay follows first order kinetics and the time required for the decay of a radioactive material is calculated as follows:
\(t=\frac{2.303}{k}\hspace{1mm}log\frac{x}{a}\)
t= time required
k= disintegration constant
x= amount of substance left after time t
a= initial amount of substance
when one half of the sample is decayed, one half of the sample remains and t can be represented as \(t_{1/2}\)
at \(t= t_{1/2}\), \(x=\frac{a}{2}\)
\(t_{1/2}=\frac{2.303}{k}\hspace{1mm}log\frac{a/2}{a}\)
\(t_{1/2}=\frac{0.693}{k}\)
