What particle is emitted in beta-minus decay, and if a sample of 14C6 (half-life = 5730 years) has 2 x 10^6 atoms, how many remain after 11,460 years?
Correct answer: B. Electron and antineutrino, 5 x 10^5 atoms
- A. Electron and neutrino, 5 x 10^5 atoms
- B. Electron and antineutrino, 5 x 10^5 atoms
- C. Positron and neutrino, 1 x 10^6 atoms
- D. Positron and antineutrino, 1 x 10^6 atoms
Explanation
In beta minus decay, a neutron decays into a proton, emitting an electron and an antineutrino. For 6C14, the number of half-lives = 11,460/5730 = 2. Remaining atoms N = N0 × (1/2)2 = 2 × 106 × 1/4 = 5 × 105.
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