Q: How many α and β – particles are emitted when nucleus 92 U238 decay to 82 Pb214 ?
Sol: Let n be the number of – particle and m be the number of – particles emitted.
92 U238 82 Pb214 + n 2 He4 + m -1 e0
As mass is conserved, 238 = 214 + 4 n + m (0)
= 214 + 4n ; 4 n = 24 ; n = 6
As charge is conserved, 92 = 82 + 2n + m (-1)
10 = 2 (6) –m (∵ n = 6) ; m = 2
6 α – particles and 2 β – particles are emitted.