Question

Compound used to remove bacteria from water is:
A. washing soda
B. baking soda
C. alum
D. bleaching powder

Answer 1

Hint: The compound is used in disinfecting swimming pools and other public places where gatherings occur. The compound is white in colour and gives away a very strong smell of chlorine.

Complete step by step solution:
In order to answer our question, let us study each of the compounds that are given in our question:
-Washing soda: Washing soda is also called sodium carbonate and it has the chemical formula $N{a}_{2}C{O}_3$. Washing soda is a salt which comes from its parent reagent that is carbonic acid. Washing soda is used in a variety of applications, but the most important use of it is in removing stains. It is so because the solubility of sodium carbonate is very high, as it is very alkaline in nature.
-Baking soda: Baking soda is also called sodium bicarbonate and it has the chemical formula $NaHC{O}_3$. It is a salt that contains $N{a}^{+}$ and $HC{O_3}^{-}$ ions respectively. It is a crystalline solid that appears white in colour. Baking soda is used in applications like baking cakes, cookies and muffins. It is basic in nature.
-Alum: Alum is a compound that is a double salt. It is a compound that is hydrated, or has water of crystallisation. Alum can be of two types: sodium alum and aluminium alum. It has the chemical formula of $XAl{(S{O}_4)}_2.12H_{2}O$, where X can be either sodium or potassium. Most widely, potassium alum is used. Uses of alum include dyeing, tanning, preparation of food and also in making clothes that are fire-proof.
-Bleaching powder: Bleaching powder is also called calcium hypochlorite and it has the chemical formula $Ca{(ClO)}_2$. It is used for the treatment of water and has more chlorine than other compounds which are used as bleaching agents. So, a strong smell of chlorine comes. It appears as a white solid.

Hence, the correct answer would be option D.

Note: Washing soda and alum also have little bit of bleaching properties and can be used in treatment of water. Bleaching powder decomposes slowly in air and is insoluble in hard water.