Radioactivity — Question 16

$_{85}^{222}\text{R}$ before the emission of β particle, would have atomic number 84, and before 2 α emissions, atomic number would have been 88. Hence, atomic number (Z) = 88.

$_{85}^{222}\text{R}$ before the emission of β particle, would have mass number 222, and before 2 α emissions, mass number would have been 230. Hence, mass number (A) = 230.