The temporary hardness of water due to calcium carbonate can be removed by adding —
A.
$$CaC{O_3}$$
B.
$$Ca{\left( {OH} \right)_2}\,$$
C.
$$CaC{l_2}$$
D.
$$\,HCl$$
Answer :
$$Ca{\left( {OH} \right)_2}\,$$
Solution :
Temporary hardness of water is due to presence of bicarbonates of $$Ca$$ and $$Mg$$ and it is removed by adding
$$Ca{\left( {OH} \right)_2}$$ to hard water and precipitating these soluble bicarbonates in the form of insoluble salts.
$$\eqalign{
& Ca{\left( {HC{O_3}} \right)_2}\mathop \to \limits^\vartriangle CaC{O_3} \downarrow + C{O_2} \uparrow + {H_2}O \cr
& Mg{\left( {HC{O_3}} \right)_2}\mathop \to \limits^\vartriangle Mg{\left( {OH} \right)_2} \downarrow + 2C{O_2} \uparrow \cr} $$
Releted MCQ Question on Inorganic Chemistry >> P - Block Elements
Releted Question 1
The reddish brown coloured gas formed when nitric oxide is oxidised by air is