For Question 1, Ideas that are Science based, are often testable, verifiable, can be falsified, and based on evidence.
Ideas that are non-science based are not testable, not verifiable, said to be infallible and are based on belief.
For Question 2, The gravitational force increases as the size of an object increases. On the other hand, the strength of gravity is inversely related to the square of the distance between two objects.
For Question 3, The equation from density is mass over volume.
Changes volume it will change by a inverted proportion. Increases it will decrease the density, decreasing it wil increase the density.
Changes mass it will change directly. Increasing mass it will increase density and vice versa.
For Question 4, Examples of physical properties are: color, smell, freezing point, boiling point, melting point, infra-red spectrum, attraction (paramagnetic) or repulsion (diamagnetic) to magnets, opacity, viscosity and density.
For Question 5, I'd say it's for proof of their theory.
Hope this helped.
