Answer:
It demonstrates that it a physical change because you can't see nothing happening but something happening
Sry if it doesn't make sense
Answer:
anthropogenic sources like landfills, agricultural activities,coal mining and combustion and some sources are natural ones
we can do soo by noticing any colour change, or by the formation of an insoluble precipitate or by the evolution of a gas.
Propene +cl2 -> 1,2 dichloropropane
