A student in CEM143 was doing a fractional distillation when she noticed that the temperature suddenly started to drop. What could have caused the decrease in the temperature

Explanation:

A process where two or more number of miscible liquids present in different fractions are separated by boiling at different temperatures is called fractional distillation.

The sudden decrease in temperature is because the compounds having lower boiling point have completed the distillation before vapor of the higher boiling point can actually fill the distillation head.

increased stability in the completion of fluorine's outer shell.

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.