A free neutron decays into a proton but a free proton does not...

A free neutron decays into a proton but a free proton does not decay into neutron. This is because

Options

Aneutron is an uncharged particle
Bproton is a charged particle
Cneutron is a composite particle made of a proton and an electron
Dneutron has larger rest mass than proton

Correct answer

D. neutron has larger rest mass than proton

Step-by-step solution

Mass of the neutron is ${m}_{n} = 1 . 67493 \times {10}^{- 27}kg$ ,

mass of the proton is ${m}_{p} = 1 . 67262 \times {10}^{- 27}kg$ .

Proton's rest mass is less than that of a neutron's rest mass. As particle can not decay to a state of greater mass, hence the proton does not decay to neutron outside nucleus whereas the neutron can decay into a proton though $\beta$ -decay.

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