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NEET 2026
Exam
NEET
Year
2026
Subject
Physics
Chapter
Chapter

NEET 2026 · Physics · Chapter

A radioactive nucleus X of mass number 220 undergoes alpha decay to...

A radioactive nucleus XX of mass number 220220 undergoes alpha decay to form a daughter nucleus YY. The binding energy per nucleon of XX is 7.4 MeV7.4 \text{ MeV}, that of YY is 7.6 MeV7.6 \text{ MeV}, and that of the alpha particle is 7.0 MeV7.0 \text{ MeV}. The energy released in this decay process is:

Options

  1. A44.0 MeV44.0 \text{ MeV}
  2. B41.6 MeV41.6 \text{ MeV}
  3. C13.6 MeV13.6 \text{ MeV}
  4. D7.2 MeV7.2 \text{ MeV}

Correct answer

B. 41.6 MeV41.6 \text{ MeV}

Step-by-step solution

The alpha decay equation is given by:

X220→Y216+α4X^{220} \rightarrow Y^{216} + \alpha^{4}

The energy released (QQ-value) in the decay process is the difference between the total binding energy of the products and the total binding energy of the reactant.

Total binding energy of XX is:

BEX=220×7.4=1628 MeVBE_X = 220 \times 7.4 = 1628 \text{ MeV}

Total binding energy of YY is:

BEY=216×7.6=1641.6 MeVBE_Y = 216 \times 7.6 = 1641.6 \text{ MeV}

Total binding energy of the alpha particle is:

BEα=4×7.0=28.0 MeVBE_\alpha = 4 \times 7.0 = 28.0 \text{ MeV}

The energy released is:

Q=BEY+BEα−BEXQ = BE_Y + BE_\alpha - BE_X

Q=1641.6+28.0−1628Q = 1641.6 + 28.0 - 1628

Q=1669.6−1628=41.6 MeVQ = 1669.6 - 1628 = 41.6 \text{ MeV}

Answer: 41.6 MeV41.6 \text{ MeV}
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