In which of the following scenarios is a chemical change taking place? * 3 points
Quartz crystal fractures when struck.
Sugar dissolves when poured into tea
Liquid water turns to a vapor at 100 degrees Celcius.
Sodium metal reacts with water to form sodium hydroxide and hydrogen gas.

The answer to this would be D. Sodium metal reacts with water

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.