NIOS Class 10 Science Activity 26.4 Air and Water Solution

 This activity explains the phenomenon of surface tension in water through a simple experiment.

Air and Water Activity 26.4 Solution

This activity is based on the NIOS Class 10 Science and Technology (212) Chapter 26 - Air and Water, Module 6 - Natural Resources.

Aim

To study the phenomenon of surface tension in water

Materials Required

   1. Glass tumbler

   2. Water

   3. Safety razor blade (with thin wax coating)

Procedure

We take a clean glass tumbler and fill it with water up to the brim. Now we place a safety razor blade on the surface of the water.

 The blade should be placed horizontally so that it does not sink in water.

Observation

 We observe that the razor blade floats on the surface.

Explanation

The upper layer of water acts like a stretched elastic sheet due to surface tension. This happens due to intermolecular forces between water molecules at the surface.

This force pulls the surface molecules inward, creating tension on the water surface; that is why the blade floats on the surface.

Conclusion

We can conclude that water has surface tension, which allows light objects to float even though they are denser than water.

Frequently Asked Questions

1.   Why does the razor blade float on water even though it is heavier than water?

Answer – Because of the surface tension of water.

2.   What is surface tension?

Answer – Surface tension is the property of liquids that makes the surface behave like a stretched membrane.

3.   What is the reason for surface tension?

Answer – Intermolecular force of attraction among molecules of liquid at the surface is the reason for surface tension.

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