__ helps to destroy animals and plants when they die, preventing them from fossilizing.
A. Carbon
B. Oxygen
C. Nitrogen
D. Hydrogen

I’m stuck on this i don’t understand.

Initially 100 milligrams of a radioactive substance was present. after 6 hours the mass had decreased by 4%. if the rate of decay is proportional to the amount of the substance present at time t, find the amount remaining after 24 hours. (round your answer to one decimal place.)

The administrator of a large assisted living facility wanted to know the average age of the residents living at the facility. he randomly selected 12 residents and determined their age, listed here: 80, 65, 75, 83, 68, 73, 88, 79, 94, 72, 79, 68 what's the average age of the sample of residents? a. 79 years old b. 68 years old c. 75 years old d. 77 years old