Two substances in a mixture differ in density and particle size. these properties can be used to
1) seperate the substances
2) chemically combine the substances
3) determine the freezing point of the mixture
4) predict the electrical conductivity

I think the best answer from the choices listed above is option 1. Two substances in a mixture differ in density and particle size. These properties can be used to separate the substances. These properties can be manipulated in order to have a better separation between the two substances.

They are all decomposition reactions.

The correct answer is c b c a d