I will mark you brainliest. I hate saying that but that's what I gotta do. Steel Wool + Oxygen (Fire)
How is mass conserved when steel wool is lit on fire?
Just give me like 2 sentences if you can. If not that's totally fine :)

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.