Chapter 26

To what height can mercury be filled in a vessel without any leakage if there is a pin hole of diameter \(0.1 \mathrm{~mm}\) at the bottom of the vessel. (Density of mercury \(=13.6 \times 10^{3} \mathrm{~kg} \mathrm{~m}^{-3}\), surface tension of mercury \(=550 \times 10 \mathrm{~h}^{-3} \mathrm{pNm}^{-1}\), Angle of contact with the vessel for mercury \(=0^{\circ}\) ) (A) \(16.1 \mathrm{~cm}\) (B) \(18.5 \mathrm{~cm}\) (C) \(20 \mathrm{~cm}\) (D) \(12.5 \mathrm{~cm}\)

A spherical soap bubble of radius \(2 \mathrm{~cm}\) attached to the outside of a spherical bubble of radius \(4 \mathrm{~cm}\). Then what is the radius of the common surface? (A) \(3.5 \mathrm{~cm}\) (B) \(4 \mathrm{~cm}\) (C) \(4.5 \mathrm{~cm}\) (D) \(3 \mathrm{~cm}\)

By how much depth will the surface of a liquid be depressed in a glass tube of radius \(0.2 \mathrm{~mm}\) if the angle of contact of the liquid is \(135^{\circ}\) and the surface tension is \(0.547 \mathrm{Nm}^{-1}\) ? (Density of the liquid is \(1.28 \times 10^{4} \mathrm{~kg} \mathrm{~m}^{-3}\) ) (A) \(3 \mathrm{~cm}\) (B) \(4 \mathrm{~cm}\) (C) \(5 \mathrm{~cm}\) (D) \(2 \mathrm{~cm}\)