If you add the valences of each atom in the molecular formula for arsenious acid, H 3 AsO 3, you can see that the molecule, which is uncharged, has a total valence state of 0 (3x(+1) for the hydrogen atoms; 1x(+3) for the arsenic(III) atom; 3x(-2) for the oxygen atoms = 3+3-6 = 0).
Eighty percent of sewage in India is untreated and flows directly into the nation's rivers, polluting the main sources of drinking water, a study by an environment watchdog showed Tuesday.
Water is polluted when it becomes contaminated from sources such as runoff, toxic chemicals and sewage leaks. Pollution may be either point source, which is when the pollution comes from a single source of origin, or it may be non-point source, which is when it comes from multiple sources over a large area.