Inside two conical pipes there is a drop of water (Figure (a)) and a drop of mercury (Figure (b)). Where does each drop lend to move? 2.53. Which of the curves shown ill the figure depicts correctly the temperature dependence of surface tension? Curve 1 falls off to zero at the boiling- point of the liquid, curve 2 falls off to zero at the critical temperature, curve 3 tends to zero asymptotically, and curve 4 shows that surface tension is temperature independent.