Define symbol and compound with an exomple.​

Symbol: A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. For example, a red octagon is a common symbol for "STOP"; on maps, blue lines often represent rivers; and a red rose often symbolizes love and compassion.

Compound: a thing that is composed of two or more separate elements; a mixture.
For Example: water (H2O), salt (sodium chloride, NaCl), methane (CH4).

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.

The answer is a. mars