i. Corrosion: The process of slow degradation of the metals due to the attack of atmospheric gases, moisture, acids, etc. on the surface of metals is called corrosion. eg. Iron forms reddish brown coloured coating on its outer surface due to corrosion.
ii. Rancidity: The oxidation of oils and fats in foods resulting into a bad smell and bad taste is called rancidity. As a result of this oxidation, the food becomes rancid and unfit for consumption.
eg. Cooking oil kept for long time will become rancid.
