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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 maximum energy that a positron can possess during the...

Determine the maximum energy that a positron can possess during the β+\beta^{+}-decay of ^{11}\text{C}into11Binto ^{11}\text{B}. The atomic masses of ^{11}\text{C}and11Band ^{11}\text{B} are 11.0114 u11.0114 \text{ u} and 11.0093 u11.0093 \text{ u}, respectively.

Options

  1. A1444.3 keV1444.3 \text{ keV}
  2. B866.4 keV866.4 \text{ keV}
  3. C933.6 keV933.6 \text{ keV}
  4. D1955.1 keV1955.1 \text{ keV}

Correct answer

C. 933.6 keV933.6 \text{ keV}

Step-by-step solution

The β+\beta^{+} decay equation is given by:

^{11}_{6}\text{C} \rightarrow ^{11}_{5}\text{B} + e^{+} + \nu_{e}<br><br>TheQ−valueofthereactionis:<br><br><br><br>The Q-value of the reaction is:<br><br>Q = [m_{N}(^{11}\text{C}) - m_{N}(^{11}\text{B}) - m_e]c^2<br><br>Expressingnuclearmassesintermsofatomicmasses:<br><br><br><br>Expressing nuclear masses in terms of atomic masses:<br><br>m_{N}(^{11}\text{C}) = m(^{11}\text{C}) - 6m_e<br><br><br><br>m_{N}(^{11}\text{B}) = m(^{11}\text{B}) - 5m_e<br><br>SubstitutingtheseintotheQ−valueequation:<br><br><br><br>Substituting these into the Q-value equation:<br><br>Q = [m(^{11}\text{C}) - 6m_e - (m(^{11}\text{B}) - 5m_e) - m_e]c^2<br><br><br><br>Q = [m(^{11}\text{C}) - m(^{11}\text{B}) - 2m_e]c^2<br><br>Givenvalues:<br><br><br><br>Given values:<br><br>m(^{11}\text{C}) = 11.0114 \text{ u}<br><br><br><br>m(^{11}\text{B}) = 11.0093 \text{ u}<br><br><br><br>m_e = 0.0005486 \text{ u}<br><br>Calculatingthemassdefect:<br><br><br><br>Calculating the mass defect:<br><br>\Delta m = 11.0114 - 11.0093 - 2(0.0005486)<br><br><br><br>\Delta m = 0.0021 - 0.0010972 = 0.0010028 \text{ u}<br><br>Usingtheconversionfactor<br><br>Using the conversion factor1 \text{ u} = 931 \text{ MeV}/c^2:<br><br>:<br><br>Q = 0.0010028 \times 931 \text{ MeV}<br><br><br><br>Q = 0.9336 \text{ MeV} = 933.6 \text{ keV}<br><br>ThemaximumkineticenergyofthepositronisequaltotheQ−valueofthereaction,whichis<br><br>The maximum kinetic energy of the positron is equal to the Q-value of the reaction, which is933.6 \text{ keV}.<br><br>Answer:.<br><br>Answer:933.6 \text{ keV}
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