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Concepts Of Physics MCQ Edition [Volume 2]
Exam
Concepts Of Physics MCQ Edition [Volume 2]
Subject
Physics
Chapter
The Nucleus

Concepts Of Physics MCQ Edition [Volume 2] · Physics · The Nucleus

Determine the Q -value for the fusion reaction: ^ 2 _ 1 H + ^ 2 _ 1...

Determine the QQ-value for the fusion reaction:
^{2}_{1}\text{H} + ^{2}_{1}\text{H} \to ^{3}_{1}\text{H} + ^{1}_{1}\text{H}<br>Atomicmassesaregivenas<br>Atomic masses are given asm(^{2}_{1}\text{H}) = 2.014102 \text{ u},,m(^{3}_{1}\text{H}) = 3.016049 \text{ u},,m(^{3}_{2}\text{He}) = 3.016029 \text{ u},and, andm(^{4}_{2}\text{He}) = 4.002603 \text{ u}.

Options

  1. A2.02 MeV2.02 \text{ MeV}
  2. B8.10 MeV8.10 \text{ MeV}
  3. C4.05 MeV4.05 \text{ MeV}
  4. D3.25 MeV3.25 \text{ MeV}

Correct answer

C. 4.05 MeV4.05 \text{ MeV}

Step-by-step solution

The given fusion reaction is:
^{2}_{1}\text{H} + ^{2}_{1}\text{H} \to ^{3}_{1}\text{H} + ^{1}_{1}\text{H}<br><br>Tofindthe<br><br>To find theQ−valueofthereaction,wefirstcalculatethemassdefect(-value of the reaction, we first calculate the mass defect (\Delta m).Thestandardatomicmassofhydrogen(11H). The standard atomic mass of hydrogen (^{1}_{1}\text{H}) is approximately 1.007825 u1.007825 \text{ u}.

The total mass of the reactants is:
mreactants=2×m(12H)=2×2.014102 u=4.028204 um_{\text{reactants}} = 2 \times m(^{2}_{1}\text{H}) = 2 \times 2.014102 \text{ u} = 4.028204 \text{ u}

The total mass of the products is:
mproducts=m(13H)+m(11H)=3.016049 u+1.007825 u=4.023874 um_{\text{products}} = m(^{3}_{1}\text{H}) + m(^{1}_{1}\text{H}) = 3.016049 \text{ u} + 1.007825 \text{ u} = 4.023874 \text{ u}

The mass defect Δm\Delta m is:
Δm=mreactants−mproducts\Delta m = m_{\text{reactants}} - m_{\text{products}}
Δm=4.028204 u−4.023874 u=0.004330 u\Delta m = 4.028204 \text{ u} - 4.023874 \text{ u} = 0.004330 \text{ u}

The QQ-value is calculated by multiplying the mass defect by 931.5 MeV/u931.5 \text{ MeV/u}:
Q=Δm×931.5 MeV/uQ = \Delta m \times 931.5 \text{ MeV/u}
Q=0.004330×931.5≈4.033 MeVQ = 0.004330 \times 931.5 \approx 4.033 \text{ MeV}

Depending on the exact rounded value of the mass of ^{1}_{1}\text{H}usedinstandardtextbookproblems(oftentakenasused in standard textbook problems (often taken as1.0078 \text{ u}),thecalculated), the calculatedQ−valuecomesouttobeapproximately-value comes out to be approximately4.05 \text{ MeV}.Theclosestgivenoptionis. The closest given option is4.05 \text{ MeV}.<br><br>Answer:.<br><br>Answer:4.05 \text{ MeV}
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