Question

the table below shows some behaviors of water that might be observed in nature or in a laboratory. which behavior is an example of surface tension? 1. laying below a layer of oil in an erlenmeyer flask 2. supporting the weight of a water insect in a pond 3. dissolving a sample of sodium chloride in a beaker 4. moving up a strip of paper during chromatography 5. climbing the side of a glass graduated cylinder 6. vaporizing from a body of water on a cold morning

Explanation:

Step1: Recall surface tension concept

Surface tension is the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules.

Step2: Analyze each option

• Option 1 (layering oil): This is about density difference (oil less dense than water), not surface tension.
• Option 2 (supporting insect): Water’s surface tension creates a “skin - like” layer that can support the weight of a water insect (e.g., water strider).
• Option 3 (dissolving NaCl): This is about solubility (ion - dipole interactions), not surface tension.
• Option 4 (paper chromatography movement): This is capillary action (adhesion and cohesion), not surface tension.
• Option 5 (climbing glass): This is meniscus formation (adhesion and cohesion), not surface tension.
• Option 6 (vaporizing): This is about phase change (energy input to break intermolecular forces), not surface tension.

Answer:

1. Supporting the weight of a water insect in a pond.