Safety goggles! Wouldn't want to get sulfuric acid in your eyes
For the first question, I would say a line graph. And the one about the human heart, I need some more information.
Answer:
The heart has four chambers: The right atrium receives blood from the veins and pumps it to the right ventricle. The right ventricle receives blood from the right atrium and pumps it to the lungs, where it is loaded with oxygen. The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle.
Explanation:
A carbon atom can form a maximum of 4 single covalent bonds