Which of the following is not a function of the circulatory system?
1. breaks down large molecules
2. delivers oxygen to body cells
3. takes carbon dioxide away from body cells
4. fights infection

i'd say that the moon rock is about 2.2 billion years old.

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds