Corrosion: Metals when kept exposed, it reacts with air moisture, acids and other gases present in atmosphere and get corrode. This process is called corrosion. Rusting: Iron metal when left exposed, it reacts with moisture and air and get coated with reddish brown powdery substance called rust, this process is called rusting. Rancidity: Food containing fats and oil when exposed to air gets oxidised and gives bad taste and smell to food. This process is called rancidity
