Question

Ever iron get rusted,we are using for building constructions as a traditional metal.is it correct if not suggest alternate metals.
explain the chemical formula of the compounds by crisis-cross method

Answer 1

as I have already told about the iron that became rusted in building construction but as your questions is about the chemical formula of the compound by Criss cross method is as follow:-
first write the valencies of the element that is in the compound and its element symbol
then Criss cross the valency is and write the subscript below the element symbol.
example:-. H. O
1. 2
Criss cross the valencies as the hydrogen has valency 1 and oxygen has valency 2 so we get H2O
H2O

Answer 2

Hi thank you for asking the question
Rusting in metal is due to its reaction with the moisture.
Is some way we can expel all water near the metal than the rusting would stop. Another way is that we can cover iron in small thin layer of some other solid that would stop the contact of iron with metal.
Steel is such a metal that do not get rusted easily but it is costly