Define a unit cell

Define unit of electric energy?

The density of potassium bromide crystal is 2.75 g cm^(-3) and the length of an edge of a unit cell is 654 pm. The unit cell of KBr is one of three types of cubic unit cells. How many formula units of KBr are there in a unit cell ? Does the unit cell have a NaCl or CsCl structure ?

If all three iterfacial angeles defining the unit cell, are equal in magniture, the crystal cannot be:

Define the unit of electric potential.

Define unit vector.