61. A hydrogen balloon floats up because of A.Air pressure decreases with decrease in height B.Air pressure decreases with decrease in weight C.Weight of the balloon is less than the weight of air displaced by it. D.The pressure inside the balloon is more than the pressure outside it
Option C Solution: The balloon has to displace some air, so in response, the air pushes up on it. But hydrogen is less dense than air, so the air pushes up on the balloon harder than gravity is pulling it down, and the balloon tries to move up. So just like wood float on water, hydrogen balloons float on air.
