Hlo everyone
plz give me answer :-
1) What do u mean by rusting of iron ?

Rusting of iron refers to the formation of rust, a mixture of iron oxides, on the surface of iron objects or structures. This rust is formed from a redox reaction between oxygen and iron in an environment containing water (such as air containing high levels of moisture).

Inner Transition Elements: Displacement Reaction

Ozone Layer Definition: General Formula Of Alcohol

Rusting is an oxidation reaction. The iron reacts with water and oxygen to form hydrated iron(III) oxide, which we see as rust. Here is the word equation for the reaction: iron + water + oxygen → hydrated iron(III) oxide.

Explanation:

Hope It Helps Ya ItzAlex

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.