Question

Water rises to a height of 10cm in a capillary tube and mercury falls to a depth of 3.42 cm in the same capillary tube. If the density of mercury is 13.6 and the angle of contact of mercury and water are 135⁰ and 0° respectively, then the ratio of surface tensions of water and mercury is

• A. 1 : 0.15
• B. 1 : 3
• C. 1 : 6.5
• D. 1.5 : 1

Answer 1

Answer: (C)

1 : 6.5

Answer 2

h =

or S =

or S ∝ $\frac { \mathrm { h } \rho } { \cos \theta }$

Putting the values, we obtain

1 : 6.5

Hence, (3) is the correct choice.