Question

If for a liquid in a vessel, force of cohesion is twice the force of adhesion, then identify the correct statement(s):

• A. The meniscus will be convex upwards
• B. The angle of contact will be obtuse
• C. The liquid will descend in the capillary tube
• D. The liquid will wet the surface of the vessel

Answer 1

Answer: (A), (B), (C)

The liquid will descend in the capillary tube

When force of cohesion is twice the force of adhesion, the liquid does not wet the sides of the vessel. It tends to repel from the contact surface rather than spreading on it.

In this case, angle of contact will be obtuse $(\theta >{90}^{\circ })$ & the shape of the liquid meniscus will be convex upward.
i.e $\cos \theta \to -ve$.
$h=\frac{2T\cos \theta }{rg\rho }$
Hence, $h$ will be $-ve$ which means that the liquid level will fall in the capillary tube inserted in the vessel.
$\therefore$ Options $\left(a\right),\left(b\right),\left(c\right)$ are correct.