Which statement best describes science

Which statement best explains why an object weight less on mercury than it does on earth

"an open tank has the shape of a right circular cone. the tank is 6 feet across the top and 5 feet high. how much work is done in emptying the tank by pumping the water over the top edge? note: the density of water is 62.4 lbs per cubic foot."

What causes the development of most clouds and precipitation in the atmosphere?