Doubtclip is an AI tutor that turns any homework or exam doubt into a step-by-step whiteboard video lesson with diagrams, formulas, and voice explanation.

Which subjects and exams does it support?

It supports Physics, Chemistry, Mathematics/Calculus and related STEM doubts for school boards, JEE, NEET, and global high-school / undergrad practice.

How do I get a video solution?

Upload a photo of the question or paste the text, sign in, and Doubtclip generates a whiteboard-style explanation video you can watch and share.

Is Doubtclip available worldwide?

Yes. Doubtclip is a web app for students globally. Lessons are available in English and Hinglish.

Given the masses of various atomic particles mP=1,0072 u, mn=1,0087 u, me=0.000548 u, m v=0, md=2.0141 u, where p=proton, n neutron, e electron, v antineutrino and d deuteron. Which of the following process is allowed by momentum and energy conservation :

n+n→ deuterium atom (electron bound to the nucleus)

Atoms & Nuclei

JEE Main level, single correct, medium

228 of 239

Question 228 of 239

Given the masses of various atomic particles ${m}_{P}=1,0072 u$ , ${m}_{n}=1,0087 u$ , ${m}_{e}=0.000548 u$ , ${m}_{\bar{v}}=0$ , ${m}_{d}=2.0141 u$ , where $p=$ proton, $n\equiv$ neutron, $e\equiv$ electron, $\bar{v}\equiv$ antineutrino and $\bar{d}\equiv$ deuteron. Which of the following process is allowed by momentum and energy conservation :

Show answer and solution

Answer: (C) $n+p\rightarrow d+\gamma$

For

n+p\rightarrow d+\gamma

,
The mass defect,

∆m={m}_{p}+{m}_{n}-{m}_{d}

\Rightarrow ∆m=1.0072+1.0087-2.0141

\Rightarrow ∆m=0.0018

\Rightarrow ∆m\gt 0

∴onlyn+p\rightarrow d+\gamma ispossible

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.

See it move: Atoms: Rutherford, Bohr and X-rays simulationDrag the sliders and watch the numbers in this question change.Revise Modern Physics firstFormula sheet, solved examples and the traps students fall into.

More Physics practice

JEE Main Physics practice question on Atoms & Nuclei (Nuclear reactions), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.