Define the terms mass and weight.

Mass — The mass of a body is the quantity of matter it contains.

It is a scalar quantity and it's S.I. unit is kg.

Weight — The weight of a body is the force with which the earth attracts it. In other words, weight of a body is the force of gravity on it.

Weight is a vector quantity. It's direction is downwards towards the centre of the earth.

Unit of weight — S.I. unit of weight is newton (N).