Ammonia is a poisonous, colourless gas with a pungent smell. Mainly …

Sulfur Sources sulfur By-product of petroleum and natural gas refining Occurs …

The Periodic table is a method of classifying elements. Elements are …

Valences of each elemental group Group Valency I 1 II 2 …

Exothermic reactions reactions which gives out energy the surroundings gain energy …

Main pollutants Carbon monoxides from unburnt hydrocarbons, exhaust fumes sulphur dioxide …

Uses of water domestic: drinking, cooking, washing, farming etc. industry: irrigation, …