I have got this problem in my text book,
Consider these three mercury manometers. One of them has 1 mL of water placed on top of the mercury, another has 1 mL of a 1 m urea solution placed on top of the mercury, and the third one has 1 mL of a 1 m NaCl solution placed on top of the mercury. Identify X, Y, and Z with these solutions.
I got the answer in answer sheet is X = ${H_2}O$ , Y = $NaCl$ and Z = ${(NH_2)}_2{CO}$ . Can any one please explain me? Thanks in advance.