What chemical change occurs when iron is exposed to oxygen and water for a long time?
Answer variants:
dry air alone
rusting
deposits to develop
water alone
presence of both air and water
rust
brown deposits
The or discolouration on the iron nails do not develop when the iron nail is kept in or . However, when the iron nail is kept in the , it develops brown deposits. This indicates that the presence of both water and air is essential for these . Thus, moist air is responsible for the formation of brown deposits on iron objects. This brown deposit is called . The formation of rust on iron objects is called .