How does the force of gravity between two bodies change when the distance between them is doubled?

According to social exchange theory, altruistic behaviors benefit the individual who performs them. t/f

Hydrogen and helium are both members of?

Water is siphoned from a large tank and discharges into the atmosphere through a 50-mm diameter tube. the end of the tube is b = 2.1 m below the tank bottom which is a = 7.4 m deep, and viscous effects are negligible. determine the maximum height h over which the water can be siphoned without cavitation occurring. atmospheric pressure is 101.4 kpa, and the water vapor pressure is 1.79 kpa (absolute)