Which of these is an example of a chemical change? melting ice on the windshield
burning gasoline
breaking glass
denting a bumper

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added

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.