" Oil and fat containing food items are flushed with nitrogen.Why? (1) "

(a) Write one equation each for decomposition reaction when energy is supplied in the form of : (i) heat , (ii) light. (b) Account for the following : (i) Paint is applied on iron articles. (ii) Oil and fat containing food items are flushed with nitrogen . (iii) When an iron nail kept in copper sulphate solution, blue colour of the solution fades and iron nail becomes brownish .

Oils and fats are :

Why the smell and taste of food items change?