Question

The mass of $\alpha$-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

$\alpha$-particle = $_2He^4$. It contains 2 p and 2 n. As some mass is converted into binding energy, therefore, mass of a particle is slightly less than sum of the masses of 2p and 2n