Question

The capillary action for various liquid-solid pairs is given below.
Match the correct meniscus, angle of contact and what happens to the level of liquid.

$\begin{array}{ccc}& & \\ \text{Meniscus}& \text{Angle of contact}& \text{Level}\\ \text{(A) Concave}& \left(i\right)\theta >{90}^{\circ }& \left(a\right)\text{Fall}\\ \text{(B) Plane}& \left(ii\right)\theta <{90}^{\circ }& \left(b\right)\text{No rise or fall}\\ \text{(C)Convex}& \left(iii\right)\theta ={90}^{\circ }& \left(c\right)\text{Rise}\end{array}$

• A. $\left(A\right)\to \left(iii\right)\to c$
• B. $\left(B\right)\to \left(iii\right)\to \left(a\right)$
• C. $\left(A\right)\to \left(ii\right)\to \left(c\right)$
• D. $\left(C\right)\to \left(ii\right)\to \left(a\right)$

Answer 1

The correct option is C $\left(A\right)\to \left(ii\right)\to \left(c\right)$

The nature of meniscus formed depends on the contact angle. The contact angle is measured with respect to the capillary tube.


Hence, for a concave miniscus, angle of contact is $\theta <{90}^{\circ }$ and water level will rise in the capillary tube.
For a convex miniscus, angle of contact is $\theta >{90}^{\circ }$ and water level will fall in the capillary tube.
For a plane miniscus, angle of contact is $\theta ={90}^{\circ }$ and water level will neither rise nor fall.

Option (C) is the correct one.