Please give definition for organic and inorganic impurities.
Organic matter mainly consists of carbon and its compounds which are released by human discharges or natural sources. For e.g. human faeces, vegetable peels, etc. they all are natural and organic.
Inorganic impurities refer to the impurities which are not organic in nature and consist of some major ions like nitrate, phosphate, etc.
You will be studying more about these concepts in your higher grades.
Hope it helps.