Question

To determine the half-life of a radioactive element, a student plots a graph of In |dN(t)/dt| versus t. Here dN(t)/dt is the rate of radioactive decay at time t. If the number of radioactive nuclei of this element decreases by a factor of p after 4.16 years, the value of p is

Answer 1

Slope of line = - 1/2,

∴ λ = 12 yr-1, t1/2 = 0.693/λ =1.386 yr

4.16 yr = 3t1/2, ∴ p =23 = 8.