Which method can best be used to confirm the presence of a colloidal mixture due to the Tyndall effect?
Shining a beam of light through the mixture and observing scattered light
The Tyndall effect is the scattering of a beam of light by the particles of a colloid. Colloidal particles (about 1–1000 nm) are large enough to scatter light, so the path of the beam becomes visible inside the mixture. In a true solution the particles are too small and the beam passes through unseen.
So, to confirm a colloid, a beam of light (for example a torch or laser) is passed through the mixture and the illuminated path is observed from the side.
Heating to evaporate the solvent only shows that something is dissolved or dispersed; filter paper cannot separate colloidal particles from either solutions or colloids; and standing undisturbed only separates suspensions, since colloids do not settle. None of these involve scattering of light.
Hence, the method is shining a beam of light through the mixture and observing scattered light.
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The following item consists of two statements, Statement I and Statement II. Examine these two statements carefully and select the correct answer using the code given below :
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Statement II : When a catalyst is in the powdered form, its surface area becomes highestOn adding some detergent to water, the surface tension
- The process by which a chemical change takes place in a substance when electric current is passed through it is called
