Question

In $\beta^-$ decay, a neutron transforms into a proton within the nucleus according to the equation:
neutron $\to$ proton + $\beta^-$ + $x$
In this equation the particle represented by 'x' is

• A. Neutrino
• B. Anti neutrino
• C. Positron
• D. Meson

Hint:

$\beta^-$ decay produces an antineutrino. $\beta^+$ decay produces a neutrino.

Answer 1

The Correct Option is B

Step 1: Conservation Laws:
In beta decay (specifically $\beta^-$ decay), a neutron turns into a proton and an electron (beta particle). To conserve spin and lepton number, another particle is emitted. $n \to p + e^- + \bar{\nu}_e$ The electron has lepton number +1. To keep total lepton number zero (as for neutron), the emitted particle must have lepton number -1. This is the antineutrino ($\bar{\nu}_e$).