Question

Two deutrons fuse to form a helium nucleus and energy is released, because the mass of helium nucleus is

• A. equal to that of two deutrons
• B. less than that of two deutrons
• C. more than that of two deutrons
• D. all the above

Answer 1

Answer: (B)

less than that of two deutrons

Mass of deuteron nucleus is 2.0141 amu and masss of helium nucleus is 4.0026 amu. When two deuterons fuse to form a helium nucleus some of the mass will be lost and the mass defect is
$\Delta m=(2\times 2.0141)-4.0026$
$\Delta m=4.0282-4.0026$
$\Delta m=0.0256amu$
This mass is converted into energy and is released.
Hence, two deuterons fuse to form a helium nucleus and energy is released, because the mass of helium nucleus is less than that of two deuterons