Question

The mass of an α-particle is.

• A. Less than the sum of masses of two protons and two neutrons
• B. Equal to mass of four protons
• C. Equal to mass of four neutrons.
• D. Equal to sum of masses of two protons and two Neutrons.

Answer 1

Answer: (A)

Less than the sum of masses of two protons and two neutrons

Answer 2

This is due to mass defect because a part of mass is used in keeping the neutrons and protons bound as $\alpha -$particle.