What is the attraction between molecules of the same substance called?

• A. Adhesion
• B. Cohesion
• C. Ionic bond
• D. Covalent bond

Answer: (B)

The attraction between like molecules within a substance is cohesion. This is due to intermolecular forces that pull molecules toward one another. In water, for example, hydrogen bonds between molecules create cohesion, giving water high surface tension and the ability to form droplets and to move up narrow tubes via capillary action. This differs from adhesion, which is the attraction between unlike substances (water sticking to glass). Ionic and covalent bonds are chemical bonds that hold atoms together within or between molecules, not the intermolecular attractions that keep separate molecules of the same substance linked together. So cohesion is the term for the pull between molecules of the same substance.