Why Apparent weight of substance is less than it Real weight?

The apparent weight is less than that of the real weight because of buoyancy.

Explanation:

Buoyancy is the upward thrust that is experienced by the object that is either fully or partially immersed in the object. The weight of the immersed object will be equal to the mass of the liquid that is displaced by the object. Buoyancy can be calculate based on Archimedes's Principle. Buoyancy also acts in the air, the normal force is reduced than the force of gravity. Buoyancy is the ability to float in liquid as well as in air. This floating happens when various forces acts on the opposite direction. The direction of the force will always remain upwards.