Which is the main chemical element present in coal and petroleum?
Name two alloys of iron. What elements are present in these alloys?
___ is the main chemical element present in coal and petroleum.
(a) Name two metals which are found in nature mainly in the free state (as metallic elements). (b) Name two metals which are always found in the combined state. (c) What iron compound is present in haematite ore? Also, write its chemical formula.