1. Edible oil is not allowed to stand for a long time in an iron or tin container.
Ans.
i. If edible oil is allowed to stand for a long time in an iron or tin container the fatty acids in the oil react with rust flakes or powder to form salts.
ii. These salts contaminate the oil and hence the oil becomes rancid.
iii. Rancid oils have a foul odour and unpleasant taste.
iv. Thus, rancid oil is of no use. Hence, Edible oil is not allowed to stand for a long time in an iron or tin container to avoid rancidity.