Question

A nuclei $X$ with mass number $A$ and charge number $Z$, disintegrates into one $\alpha$-particle and one $\beta$-particle. The resulting nuclide $R$ has atomic mass and atomic number, equal to :

• A. (A - Z) and (Z - 1)
• B. (A- Z) and (Z- 2)
• C. (A - 4) and (A - 2)
• D. (A - 4) and (Z- 1)

Answer 1

Answer: (D)

(A - 4) and (Z- 1)

Answer 2

When an $\alpha$-particle is emitted, mass number of nuclide $X$ is reduced to $4$, and its charge number is reduced to $2$, But when a $\beta$-particle is emitted, mass number of remains the same and its charge number is increased by $1$. Hence, the resulting nuclide has atomic mass $A-4$ and atomic number $Z-1$.