Unit cells provide the simplest repeating structures of a crystal. This means a unit cell must contain an integer multiple of the empirical formula. a. True
b. False

True

Explanation:

The unit cell is the smallest group of atoms which has the overall symmetry of a crystal, and from which the entire lattice can be built up by repetition in three dimensions (Oxford dictionary).

The number of atoms in a unit cell of a crystal structure must be equal to or a multiple of the number of atoms in the empirical formula of the compound. In other words, the unit cell should contain the formula unit of the compound.

c is the answer because when something is left after something evaporates that shows the chemical change.

what is the question?