What subatomic particles are found in the nucleus of an atom

Explanation:

The subatomic particles of protons and neutrons are found in the nucleus of an atom. Protons are particles with a positive charge, while neutrons have no charge. Electrons, which have a negative charge, are particles that can found orbiting outside the nucleus of an atom.

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.