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JEE Main 2020 (4 Sep, Shift 2) · Mass Defect & Binding Energy

Mass Defect & Binding Energy question from JEE Main 2020 (4 Sep, Shift 2)

Q18JEE Main 2020 · 4 SEP · SHIFT 2Easy

Mass Defect & Binding Energy

Find the Binding energy per nucleon for 50120Sn{}_{50}^{120}Sn. Mass of proton mp = 1.00783 U, mass of neutron mn = 1.00867 U and mass of tin nucleus mSn = 119.902199 U. (take 1U = 931 MeV)

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Answer: (b)

  1. Z=50Z = 50, N=120−50=70N = 120 - 50 = 70
  2. 50(1.00783)+70(1.00867)=50.3915+70.6069=120.998450(1.00783) + 70(1.00867) = 50.3915 + 70.6069 = 120.9984 u
  3. Δm=120.9984−119.902199=1.0962\Delta m = 120.9984 - 119.902199 = 1.0962 u, BE=1.0962×931=1020.6BE = 1.0962 \times 931 = 1020.6 MeV
  4. BEA=1020.6120≈8.5\dfrac{BE}{A} = \dfrac{1020.6}{120} \approx 8.5 MeV, so the answer is (b).
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