what happen when helium filled balloon rises in the air
Since the balloon would rise if released, this buoyant force must be greater than the weight of the helium-filled balloon. In other words, the weight of the helium-filled balloon is less than the weight of the volume of air it displaces, which means that it is less dense than the air it displaces. So there is a net force upwards on the balloon, equal to the difference in weight between the balloon and the volume of air that it displaces. That the helium-filled balloon experiences a net upward force means that it can lift an object whose weight does not exceed this net force.