Question

The number of \(\alpha\)-particles emitted during the radioactive decay chain from \({}^{226}_{88}\text{Ra}\) and ending with \({}^{206}_{82}\text{Pb}\) is

• A. \(5\)
• B. \(4\)
• C. \(6\)
• D. \(3\)
• E. \(2\)

Hint:

Each \(\alpha\)-decay changes: \[ A\to A-4,\qquad Z\to Z-2 \]

Answer 1

The Correct Option is A

Each \(\alpha\)-decay reduces mass number by \(4\). Initial mass number: \[ 226 \] Final mass number: \[ 206 \] Difference: \[ 226-206=20 \] So number of \(\alpha\)-particles: \[ \frac{20}{4}=5 \] Hence, \[ \boxed{(A)\ 5} \]