Rock salt is a mixture of salt and sand. describe how you would separate rock salt to obtain salt crystals and pure dry sand. this a six mark question so have six reasons in the answer.

Three point charges, two positive and one negative, each having a magnitude of 20 μc are placed at the vertices of an equilateral triangle (30 cm on a side). what is the magnitude of the electrostatic force on the negative charge

The current in a hair dryer measures 11 amps. the resistance of the hair dryer is 12 ohms. what is the voltage?unit:

Which best represents the law of conservation of mass ?