Chapter 39, Problem 16A

(a)

To determine

The effect of ejection of one alpha particle on thorium.

Explanation of Solution

Introduction:

The thorium is a radioactive element, which changes into other stable radioactive element in radioactive decay process.

The mass number reduces by four units and atomic number reduces by two unit due to ejection of one alpha particle from a radioactive element.

The thorium changes to radium due to ejection of one alpha particle because two unit of protons in the nucleus of thorium reduces and four unit of mass number reduces.

${}_{90}^{234}\text{Th}{\to }_{88}^{230}\text{Ra}{+}_2^4\alpha$

Conclusion:

Thus, the thorium changes to radium due to ejection of one alpha particle.

(b)

To determine

The effect of ejection of one beta particle on thorium.

Explanation of Solution

Introduction:

The thorium is a radioactive element, which changes into other stable radioactive element in radioactive decay process.

The mass number remains unaffected and atomic number increases by one unit due to ejection of one beta particle from a radioactive element.

The thorium changes to protactinium due to ejection of one beta particle because one unit of protons in the nucleus of thorium reduces.

${}_{90}^{234}\text{Th}{\to }_{91}^{234}\text{Pa}{+}_{-1}^0\beta$

Conclusion:

Thus, the thorium changes to Protactinium due to ejection of one beta particle.