Ineed with questions 65-67 and it’s very hard and i’m struggling with it and if you need to see the picture big then click on it and it will be big

65. Density is a physical property. The reason the oil floats on water is because oil is less dense than water, thus making it able to float.
67. The sun is our purest renewable energy source. Hence why we call solar power solar.

The correct answer is c.