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1.  The Heartlies in the front and middle of your chest, behind and slightly to the left of your breastbone.

2. Right Atrium, Left Atrium, Right Ventricle, Left Ventricle

3. The valves prevent the backward flow of blood.

4. Arteries carry oxygenated blood while veins carry deoxygenated blood.

5. Eat Healthy, Stay Active

Explanation:

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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