Point source pollution is an single source of pollution that is identifiable.
So this source can be different for different pollution that is air, water, land and noise.
Non-point source pollution:
Non-point source pollution is a pollution that results from many sources.
In the given lists of pollution only option A founds to be point source of pollution, that is dumping acid from a bucket into a lake. There is a defined single source of pollution that is acid in the bucket so it is an example of point source of pollution.
Zinc nitrate gives white ppt. which dissolves in excess ammonium hydroxide and produce a colorless solution whereas lead nitrate gives a chalky white ppt. of lead hydroxide which doesnot dissolve.
