Disintegration constant of a radioactive material is `lambda`:
A. Its half lif eequal to `(log_(e) 2)/(lambda)`
B. Its mean life equal to `1/lambda`
C. At time equal to mean life, 63% of the initial radioactive material is left undecayed
D. After 3-half lives, `1/3` rd of the initial radioactive material is left undecayed.
