Please help out especially c

Much of the general structure and physical properties of the interior of the earth are inferred from: a)deep oil and gas bore holes b)geologic investigations c)analysis of seismic waves d) study of volcanoes

If a solution is considered basic, then a) the hydroxide ion and hydronium ion concentrations are equal. b) the hydroxide ion concentration is less than the hydronium ion concentration. c) the hydronium ion concentration is greater than the hydroxide ion concentration. d) the hydroxide ion concentration is greater than the hydronium ion concentration.

How could a student test the effect of removing heat from a gas that is stored in a sealed container? what must occur in order for matter to change states?