Question

Which of the following is most unstable?

• A. Electron
• B. Proton
• C. Neutron
• D. $\alpha$ -particle

Answer 1

Answer: (C)

(a) Electron revolves around the nucleus of an atom. lt is a stable particle.
(b) Proton has positive charge and its mass is 1836 times the electronic mass. In free state, the proton is a stable particle.
(c) Neutron carries no charge. lts mass is 1839 times the electronic mass $(1.675\times 10^{-27}kg).$ In free state the neutron is unstable (its mean life is about $17\min$), but it constitutes a stable nucleus along with proton.
(d) $\alpha -$ particle is helium nucleus whose atomic number is $2$ and mass number is $4$.
Hence, out of the given four options neutron is most unstable.