Chapter 20, Problem 27QP

Interpretation Introduction

Interpretation:

The number of atoms left after $42.0\text{ min}$ is to be determined with given half-life and number of atoms.

Concept introduction:

The half-life of a reaction is defined as the time taken by the reactant concentration to decrease up to its half of its initial concentration. It is represented by $t_{1/2}$.

The numbers of elements present for 10 half-lives can be calculated by the expression: $\text{Numbers of atoms left = number of atoms initially present }\times {\left(\frac{1}{2}\right)}^{10}$