Question

The mass of an $\alpha -$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

The correct option is A less than the sum of masses of two protons and two neutrons

$\alpha$-particle is ${}_{2}H{e}^4$. It contains two protons and two neutrons. As some mass is converted into binding energy, mass of $\alpha$ particle is slightly less than the sum of the masses of two protons and two neutrons.