Question

After the emission of a β-particle followed by an α-particle from \(^{214}_{83}\text{Bi}\), the number of neutrons in the atom is:

• A. 210
• B. 128
• C. 129
• D. 82

Answer 1

The Correct Option is B

Bismuth-214 (\(^{214}_{83}\text{Bi}\)) has an atomic number of 83 and a mass number of 214.

1. Beta-particle emission: A β-particle emission raises the atomic number by 1 (83 to 84), while the mass number remains 214.
2. Alpha-particle emission: An α-particle emission lowers the atomic number by 2 (84 to 82) and the mass number by 4 (214 to 210).

The neutron count is determined by:

Number of neutrons = Mass number − Atomic number = 210 − 82 = 128