Questions

Removing the contaminents if any in the water which causes harm to our health is involved in the purifying of water. 

This process involves chemicals. Chloramines, Hydrogen peroxide, Iodine are the chemicals which are used in purifying water.

Nitrous acid act as an oxidising agent because it oxidises potassium iodide to iodine. It is also a reducing agent because it decolourises acidified potassium permanganate solution.

Nitric acid acts only as an oxidising agent

Ammonia acts only as a reducing agent

Nitrogen peroxide acts only as an oxidising agent.

SDR means Special Drawing Rights.

SDRs are a measure of a country's reserve assets with IMF and, whereas not 'money' in the strict sense, have several characteristics of money as interest-bearing assets, store of value, and means of settling indebtedness.

International financing instrument created in 1970 by the International Monetary Fund (IMF) to coincide with the disfavor of the US dollar as the principal currency of the world trade. Also called paper gold, an SDR is neither paper nor gold but an accounting entry. It is not backed by any currency or precious metal and is used only among governments and IMF for balance Of payments settlements.