What volume V of helium is needed if a balloon is to lift a load of 180 kg (includine the welght of the empty balloon)? Density of helium 0.179 kg/m pa= 1.29 kg/m

Why does karst topography exist in some geographic location? a. few climates have enough oxygen b. most regions have rock layers other than limestone c. in most regions, the soil is too thin d. the water is too acidic enough in most places