A football is inflated with 2.42 L of gas at a temperature of 301K. Later, the volume of the football has changed to 2.37 L at a temperature of 288K and a pressure of 99.7 kPa. What was the pressure when the football was inflated?

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.