Q.Write short notes on the following:

Tyndall effect = light scattered by colloidal particles making the beam visible; negative catalysis = a substance that slows a reaction down.

(i) Tyndall effect: When a strong beam of light is passed through a colloidal solution kept in a dark room, the path of the beam becomes visible as a bright illuminated cone. This is because colloidal particles are large enough to scatter light in all directions. A true solution shows no such effect (particles too small). The Tyndall effect is used to distinguish a colloid from a true solution, and the illuminated cone is called the Tyndall cone.

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