A U-tube open at both ends and made of 8 mm diameter glass tube mercury up to a height of 10 cm in both the limbs. If 19 cm3 of water is added to one of the limbs, what is the difference in mercury levels in the two limbs at equilibrium?
a. 4.5 mm b. 1.0 mm
c. 2.8 mm d. 3.2 mm