Question

what is meant by corrosion and rancidity? what is common reactant in both reactions

Answer 1

the process of rusting of metals is corrosion
the process of food get damaged is rancidity
they react with oxygen and forms oxides

Answer 2

Slowly eating up of metals by the attack of atmospheric gas or moisture is called corrosion.
Rancidity means, if the food particle contains lots of oil and after leaving it for few days, the food get rancid. This is called rancidity.
The common reactant in both these reactions are atmospheric gas and moisture