Methane, oxygen, carbon dioxide and water are the four substances.
oxygen
Hydrogen peroxide ... but its written as H2O2.
A conductor is a substance that conducts heat or electricity.
Ammonium nitrate leaves no residue when heated:NH4NO3 Δ→ N2O + 2H2O
The energy needed to change a substance from a liquid to a gas is called the enthalpy (or heat) of vaporization.
CaSO4 2H2O
A substance that does not let heat pass through it is called an insulator. Insulators are materials that have low thermal conductivity, meaning they are poor conductors of heat. This property allows them to prevent the flow of heat energy.
Two molecules of water.
The heat energy required to change a substance between solid & liquid at constant temperature is called the "latent heat of fusion". If the change is from solid to liquid the substance gains this energy. If the change is from liquid to solid the substance gives up this energy. The exact amount of latent heat of fusion is different for different substances.
Trihydrate - basically 3 molecules of water (just as dihydrate is 2H2O) Unless you're referring to the molecule 3H2O used in measuring the total body water - in that case it's 'tritiated water'
The chemical name of Plaster of Paris is calcium sulfate hemihydrate. It is produced by heating gypsum, which is calcium sulfate dihydrate, to a high temperature to remove water molecules and create a powdery substance that can be mixed with water to form a moldable paste.
sodium nitrite