Question

A radioactive decay can form an isotope of the original nucleus with the emission of particles

• A. one $\alpha$ and four $\beta$
• B. one $\alpha$ and two $\beta$
• C. one $\alpha$ and one $\beta$
• D. four $\alpha$ and one $\beta$

Answer 1

Answer: (B)

Emission of $\alpha$ particle decreases the atomic number and the mass number by $2$ and $4$ respectively. Emission of $\beta$ -particle increases the atomic number by $1$ while the mass number remains unchanged. Therefore, after the emission of one $\alpha$ and two $\beta$ -particles, the atomic number remains the same while the mass number decreases by $4$ . Hence, the emitted nucleus is the isotope of the original nucleus.