What units do chemists normally use for the density of liquids and solids? for the density of gas? explain the differences.

Densities of the solids and the liquids are expressed in units of grams per cubic centimeter (g/cm³) or in grams per milliliter (g/mL).

Densities of the gases are usually expressed in the units of grams per liter (g/L).

Explanation:

Density of a substance can be defined as the ratio of its mass and its volume.

The constituting atoms in the solids and liquids are fairly packed closely together.

In general, a 1 cm³ or 1 mL volume of most of the solids and the liquids has mass of several grams. Thus, densities of the solids and the liquids are expressed in units of grams per cubic centimeter (g/cm³) or in grams per milliliter (g/mL).

The constituent atoms or the molecules in the gases are far apart from each other when compared to the solids and the liquids.

Thus, gases are much less dense and even about 1 L of gas have mass in range close to 1 gram. Thus, densities of the gases are usually expressed in the units of grams per liter (g/L).

Also, the density of the gases also depend upon the pressure and the temperature but these factors much not influence the density of the solids and the gases.

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