What does matter have to do with chemistry? how are forces involved?

 Matter is the thing which occupied space and volume.

Explanation:  In chemistry or in general life, we define matter as the susbtance which occupied space and make volume for itself. Thus everything on the eart occupied some kind of space thus they all are applicable to fall under the category of Matter.

There are various kinds of forces which hold together the matter depending on the type of susbtances. Like sodium chloride crystal lattice has ionic bonding between the ions whereas carbon skeleton has covalent bonding, water flowing in the river have hydrogen bonding.

These matter are made up of protons, atoms, electrons, neutrons, molecules etc.

what is the volume occupied by 40 grams of argon gas (ar) at standard conditions? what volume, in liters, is occupied by 1.5 x 1023 

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.