A free neutron decays into a proton but a free proton does not decay into neutron. This is because (a) neutron is an uncharged particle (b) neutron has larger rest mass than proton (c) neutron is a composite particle made of a proton and an electron (d) proton is a charged particle

Answer: (b). A free particle can decay only if the products have less total rest mass (energy must be released). mn > mp + me, so n → p + e⁻ + ν is allowed. mp < mn, so a free proton cannot turn into a neutron. So the answer is (b) neutron has larger rest mass than proton.

A free neutron decays into a proton but a free proton does not decay… | JEE Main 2023 (31 Jan, Shift 1)

Q13JEE Main 2023 · 31 JAN · SHIFT 1Easy

Radioactive Decays: Alpha, Beta, Gamma

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

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Answer: (b)

A free particle can decay only if the products have less total rest mass (energy must be released).
$m_n > m_p + m_e$ , so $n \to p + e^- + \bar{\nu}$ is allowed.
$m_p < m_n$ , so a free proton cannot turn into a neutron.
So the answer is (b) neutron has larger rest mass than proton.

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