Radioactive decay follows first order kinetics and the rate constant is often termed as decay constant. Certain radioactive substances may undero sequential decays in order to convert into a stable nucleus. The series comprising all such elements is termed as radioactive disintegration series.
A radioactive series is formed such that after each ` alpha` decay there are two consecutive `beta` decay and the cycle repeats. How many different elements this series can have if there are 12 members in the series ?
A. 12
B. 4
C. 3
D. 6

Radioactive decay follows first order kinetics and the rate constant is often termed as decay constant. Certain radioactive substances may undero sequential decays in order to convert into a stable nucleus. The series comprising all such elements is termed as radioactive disintegration series.
A substance A undergoes sequential decay as shown `A overset(lambda_(1))rarr B overset (lambda_(2))rarr C`. If the decay constant `lambda_(1)` and `lambda_(2)` are `4 xx10^(-2) “min”^(-1)` and `16 xx 10^(5) “min” ^(-1)` respectively then the molar ratio of B to A after a very long time will be :
A. `2.5 xx 10^(-8)`
B. `4 xx 10^(-2)`
C. `(1)/(16 )xx 10^(-5)`
D. `4 xx 10^(7)`