Stephanie is incorrect. Since fossil fuels form in the absence of oxygen, if oxygen is present, they cannot form.
(sample answer:)
Answer: The black ball will have more mass than the white ball.
Explanation: Density of a substance is defined as the ratio of mass and volume occupied by the substance.
Mathematically,

We are given that the two balls are of same size, which means that the volume of both the balls are same. We are also given that the black ball is more dense than the white ball, which means that the black ball will have more mass.
As, 
Answer:
The nuclei of most atoms also contain neutrons . The masses of subatomic particles are very tiny. ... Since the nucleus contains protons and neutrons, most of the mass of an atom is concentrated in its nucleus. Protons and electrons have electrical charges that are equal and opposite.
Charles' law (also known as the law of volumes) is an experimental gas law that describes how gases tend to expand when heated.
Probably, above 100 Degree Celsius.