A student takes three clean iron nails and places them in three different liquids.
  • Nail A is dipped in oil.
  • Nail B is dipped in water.
  • Nail C is dipped in vinegar.
The nails are left undisturbed for some days.
 
Answer the given questions:
 
1. Why does the nail kept in oil remain free from rust? - .
 
2. Which observation indicates that rusting has taken place? - .