It is easier to pull a bucket of water from the well until it is inside the water but difficult when it is out of water, why?? Anyone plz tell

When the bucket is placed inside the well and is filled with water, the water inside the well exerts an upward Buoyant Force on the bucket, being a liquid. Hence, the force exerted by gravity on the bucket as well as this buoyant force act in the opposite direction, reducing the net force on the bucket. Due to which, it is easier to lift the bucket submerged in water.

On the contrary, there is no buoyant force acting on it when it is hanging in the air, due to which we need an upward muscular force that counter-effects this gravitational force on the bucket, in order to lift it. Hence, it's a bit difficult to draw a bucket filled with water, in air.

heat the gas and measure the pressure

conservation of mass

mass before something happens = mass afterwards