Question

A radioactive nucleus undergoes a series of decays according to the scheme

$A\overset{\quad\alpha\quad}{\rightarrow}A_{1}\overset{\quad\beta\quad}{\rightarrow}A_{2}\overset{\quad\alpha\quad}{\rightarrow}A_{3}\overset{\quad\gamma\quad}{\rightarrow}A_{4}$

If the mass number and atomic number of A are 180 and 72 respectively, then what are these numbers for A₄-

• A. 172 and 69
• B. 174 and 70
• C. 176 and 69
• D. 176 and 70

Answer 1

Answer: (A)

172 and 69

Answer 2

A = 180 – 2 × 4 = 172

Z = 72 – 2 + 1 – 2 + 0 = 69