Nuclear & Particle Physics - The Sun’s Energy

The primary source of the sun’s energy is a series of thermonuclear reactions in which the energy produces is c² times the mass difference between

A. two hydrogen atoms and one helium atom
B. four hydrogen atoms and one helium atom
C. six hydrogen atoms and two helium atoms
D. three helium atoms and one carbon atom
E. two hydrogen atoms plus two helium atoms and one carbon atom

(GR0177 #19)

Solution:

In the Sun’s core, the protons of the hydrogen atoms (which largely make up the Sun) collide into each other and stick together or “fuse” to create helium nuclei.

4H → He + energy

It takes 4H nuclei to create a He nucleus due to the conservation of atomic mass.

Hydrogen atomic mass = 1 proton = 1.
Helium atomic mass = 2 protons + 2 neutrons = 4.

Answer: B