Question

Shape of the meniscus formed by two liquids when capillar­ies are dipped in in them are shown. In I it is hemispherical whereas in II it is flat. Pick correct statement regarding contact angles formed by the liquids in both situations.

• A. (a) It is 180⁰ in I and 90⁰ in II
• A. (b) It is 0⁰ in I and 90⁰ in II.
• A. (c) It is 90⁰ in I and 0⁰ in II
• A. (d) It is greater than 90⁰ in I and equal to 90⁰ in II.

Answer 1

(b)

Contact angle is the angle between tangents drawn at con­tact point, one along solid surface and another along liquid

surface. It is measured inside the liquid. In situation l, both

tangents are parallel whereas in situation II, they are at 90⁰.