Gujarat BoardEnglish MediumSTD 12 SciencePhysicsNuclei3 Marks
Question
What is meant by nuclear mass defect?
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Answer
Nuclear Mass Defect : The difference between the total mass of protons and neutrons present in the nucleus and the actual mass of the nucleus is called mass defect. $\begin{array}{l} \text { Mass defect }=\text { Mass of the nucleus obtained by } \\ \text { calculation - Actual mass of the nucleus } \\ \Delta m=m_c-m_a \end{array}$ Here, the calculated mass is abbreviated as $m _{ c }$ and the actual mass is shown as $m_a$. Therefore, $\quad \Delta m=[$ Mass of protons + Mass of neutrons] - Actual mass of nucleus or $\quad$ $\Delta m=\left[ Z \cdot m_p+(A-Z) m_n\right]-m$ where, Z is the atomic number of the atom, A is the mass number, $m_p$ is the mass of the proton, $m_n$ is the mass of the neutron and $m$ is the actual mass of the nucleus.
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