Question

fix the one word that is used incorrectly.
antarctica is the worlds largest dessert. on average it receives only 6.5 inches of precipitation every year.

Explanation:

The word "dessert" refers to a sweet food eaten after a meal, which does not fit the context of a dry, low-precipitation landmass like Antarctica. The correct term for such a landmass is "desert".

Answer:

Replace "dessert" with "desert"
Corrected sentence: Antarctica is the world's largest desert. On average it receives only 6.5 inches of precipitation every year.