Question

Which of the following formulae gives the expression for half-life of a radioactive isotope when ‘λ’ is the decay constant?

(a) 0.762/λ

(b) 0.693/λ

(c) 0.937/λ

(d) 0.258/λ

The question was asked in an interview for job.

The question is from Fundamentals of Radiochemical Methods topic in section Radiochemical Techniques of Analytical Instrumentation

Answer 1

Right choice is (b) 0.693/λ

For explanation: The formula to calculate half-life of a radioactive isotope is 0.693/λ. It is the time required for half the initial stock of atoms to decay.