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CUET · PHYSICS · PYQ PAPER 2025

The mass defect (\( \Delta M \)) for a nucleus of mass number (A), atomic number (Z) and mass (M) is given by:

  1. A \( \Delta M = [Z m_p + (A - Z) m_n] - M \)
  2. B \( \Delta M = [Z m_p + (A - Z) m_n] + M \)
  3. C \( \Delta M = [Z m_p + (A - Z) m_e] - M \)
  4. D \( \Delta M = [Z m_p + (A - Z) m_n] - M \)
Verified Solution

Answer & Solution

Correct Answer

(A) \( \Delta M = [Z m_p + (A - Z) m_n] - M \)

Step-by-step Solution

Detailed explanation

Mass defect is the difference between the total mass of the individual nucleons (protons and neutrons) and the actual mass of the nucleus ( \(M\) ). Since a nucleus has \(Z\) protons and ( \(A-Z\) ) neutrons, the sum of their individual masses is…