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 in different atoms. It 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. Its mass is $1839$ times the electric 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 a helium nucleus whose atomic number is $2$ and mass number is $4$. Hence, out of the given four options neutron is most unstable.