Physics (AS & A Level) · Oct / Nov 2025 · Paper 14 · Question 39

A nucleus of polonium, ^{214}_{84}Po, decays by emitting an α-particle to become a nucleus of lead. The nucleus of lead is also unstable and decays by emitting a β– particle to form a nucleus of bismuth which then decays by emitting a β– particle to produce a nucleus X. What is the number of neutrons in nucleus X?

1. A126
2. B128
3. C130
4. D210

As printed in the paper