Verified Solution • 2025–26 Session moderate

QJEEM20Phc821: JEE Main 2020 Physics - Class 12 JEEM20Phc821 Solution: Given the masses of various atomic particles m p = 1.0072 u, m…

Given the masses of various atomic particles
mp = 1.0072 u, mn = 1.0087 u, me = 0.000548 u,
mv‾{m_{\overline v }} = 0, md = 2.0141 u, where p ≡\equiv proton, n ≡\equiv neutron,
e ≡\equiv electron, v‾\overline v ≡\equiv antineutrino and d ≡\equiv deuteron. Which of the following process is allowed by momentum and energy conservation?

Multiple Choice Options

  • A n + n →\to deuterium atom (electron bound to the nucleus)
  • B n + p →\to d + γ\gamma
  • C p →\to n + e+ + v‾\overline v
  • D e+ + e- →\to γ\gamma

Step-by-Step Verified Solution

n + n →\to deuterium atom (This is incorrect)

Correct is n + p →\to d + γ\gamma

p →\to n + e+ + v‾\overline v
(This is incorrect as mass is increasing)

e+ + e- →\to γ\gamma (This is incorrect)

Correct is e+ + e- →\to 2 γ\gamma

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