Question

why are food stuffs containing vinegar or oil not kept in iron containetrs

Answer 1

The food stuff contains acid like vinegar. Iron is a reactive metal, it reacts with acid and forms iron salt and hydrogen is displaced . This leads to eventual eating away of metal. Thus both metal container and foodstuff are spoiled.

Fe (s) + 2 CH₃COOH (aq) $\to$ (CH₃COO)₂Fe + H₂ (g)