The surface tension and vapour pressure of water at 20oC is 7.28 × 10-2 N/m and 2.33 × 103 Pa, respectively. What is the radius of the smallest spherical water droplet which can form without evaporating at 20oC?
Correct option is B) Here, S=7.28×10−2Nm−1, P=.2.33×103Pa The drop will evaporate if the water pressure is greater than the vapour pressure P As P=R2S, where R is the radius of drop ∴R=P2S=2.33×1032×7.28×10−2=6.25×10−5m
