Question

Which is used in the following?
(i) To make drinking water free from germs.
(ii) For making tasty crispy Pakoras in kitchen.
(iii) To remove permanent hardness of water.
(iv) For making toys and decorative materials.

Answer 1

(i) Chlorine is used to make drinking water free from germs.
(ii) Sodium bicarbonate (IUPAC name: sodium hydrogen carbonate) is a chemical compound with the formula $NaHC{O}_3$. It is a salt composed of sodium ions and bicarbonate ions. Since it has long been known and is widely used, the salt has many related names such as baking soda, bread soda, cooking soda, and bicarbonate of soda.
(iii) Hard water contains dissolved magnesium and calcium ions. These make it more difficult for the water to form a lather with soap. Temporary hardness is caused by dissolved calcium hydrogencarbonate (which is removed by boiling). Permanent hardness is caused by dissolved calcium sulfate (which is not removed by boiling). Water can be softened using washing soda or an ion-exchange resin.
(iv) Plaster of Paris is used in making toys, decorative materials, cheap ornaments, cosmetic materials.