What type of chemical reaction is responsible for causing rancidity?

43 Name any three objects (or structures) which are gradually damaged by the corrosion of iron and steel. 44 Explain the term "rancidity". What damage is caused by rancidity? 44 State and explain the various methods for preventing or retarding rancidity of food. 45 What happens when an aqueous solution of sodium sulphate reacts with an aqueous solution of barium chloride?