Chapter 20, Problem 20E

Interpretation Introduction

Interpretation:

The number of half-lives has passed when a radioactive substance loses $\frac{15}{16}$ of its radioactivity is to be stated.

Concept introduction:

The elements whose nucleus decays spontaneously are known as radioactive elements. The decay is accompanied by the emission of alpha particles, beta particles, and gamma rays. All the elements which possess an atomic number greater than $83$ are radioactive. The half-life of a radioactive substance is defined as the time taken by half of its atoms to decay.