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PhysicsHardMCQ2020 · 06 Sep Shift 1

Q18.You are given that 73Li = 7. 0160u,Mass of Mass of 42He = 4. 0026u and Mass of 11He = 1. 0079H When 20g of 73Li is converted into 42 He by proton capture, the energy liberated, (in kWh ), is : [Mass of nucleon = 1 GeV /c2 ] (1) 4. 5 × 105 (2) 8 × 106 (3) 6. 82 × 105 (4) 1. 33 × 106

What This Question Tests

This question tests the ability to calculate energy released in a nuclear reaction from mass defect, convert the energy to Joules and then to kilowatt-hours, and scale it up for a given macroscopic mass of reactant using Avogadro's number.

Concepts Tested

Nuclear fusionMass defectEinstein's mass-energy equivalenceAvogadro's numberUnit conversions

Formulas Used

E = Δmc²

1 u = 931.5 MeV/c²

1 eV = 1.6 x 10⁻¹⁹ J

1 kWh = 3.6 x 10⁶ J

Number of moles = Mass / Molar mass

📚 NCERT Sections This Tests

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