If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
(a) Do you think rust is different from iron?
(b) Can you change rust back into iron by some simple method?
(c) Do you think the formation of rust from iron is a chemical change?
(d) Give two other examples of a similar type of change.

AcademicChemistryNCERTClass 7

(a) Yes, rust is different from iron. It is a brown powder of iron oxide.
(b) No rusting is a chemical change and cannot be reversed.
(c) Yes, rusting is a chemical change since a new substance is formed.
(d) (i) Burning of magnesium ribbon to give magnesium oxide.
(ii) Burning of wood to give coal and ash.
Updated on 10-Oct-2022 13:21:38