why does a cooking gas cylinder feel lighter after it has been in use for a few days ?
Cooking gas cylinders contain LPG (liquefied petroleum gas). When a cylinder is completely filled, its weight is maximum, as the fuel is in liquid form. However, since its boiling point is low, it quickly vapourises as we make use of it for cooking and the fuel gets expended. Thus, liquid evaporates and goes out of the cylinder gradually, as we use and finally, gets empty. This makes it light when the cylinder becomes empty.