It is an extremely hot day out and you are craving an iced drink. To have ice for your drink you would need to remove 1500 kj of energy from the water in the freezer. Assuming no temperature change
what would be the mass of ice made for your drink?

the answer is 75.0%.

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.