Question

Investigate the conditions required for rusting of iron
Three iron pieces put in different solutions and explain the process of working model

Answer 1

take three small iron pieces and fut them into three test tubes and name the test tube as A,B and C. in tube A put some water and leave it undisturbed. In tube B put some cotton and leave it undisturbed. In tube C put some wax and leave it undisturbed.
OBSERVATION :--- 
iron kept in test tube A is covered with a reddish brown coating of a substance called as rust.
Conclusion:-
for rusting of an piece of iron it should be in contact with oxygen.