Q16 of 41 Page 1

Explain the following terms with one example each: (a) Corrosion (b) Rancidity


(a) Corrosion: Gradual Deterioration of metals by the action of :-
1.Air
2.Moisture 
3.Chemical( such as an acid) on their surface.
Main Cause of corrosion is the oxidation of metals by the oxygen of air.
Example:- Rusting of Iron - When a piece of Iron is left out in damp time for a period of time it gets covered with a red-brown substance called rust.
The following reaction takes place resulting in then formation of rust:-


(b) Rancidity:- Oxidation of Fats and Oils present in food materials by the oxygen present in air resulting in unpleasant smell and taste is called Rancidity. This makes the food not fit for eating.
Example:- Potato Chips that are cooked in oil turn Rancid and give out unpleasant smell and taste if kept exposed for a long time

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Identify the type of chemical reaction taking place

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ii. on heating green coloured ferrous sulphate crystals, reddish-brown solid is left and the smell of a gas having the odour of burning Sulphur is observed.