Temporary hard water is formed when rain water containing dissolved carbon(IV) oxide flows over deposits of
-
A.
CaCO3 -
B.
Na2CO3 -
C.
Na2SO4 -
D.
CaSO4
Correct Answer: Option A
Explanation
Permanent hardness in water= Mg & Ca Sulphate.
Temporary hardness in water= Mg & Ca Carbonate.
Temporary hardness of water is caused by Magnesium and calcium hydrogencarbonate. It is formed when rainwater containing dissolved CO2 flows over deposit of CaCO3
i.e CaCO3 + CO2 + H2O → Ca(HCO3)2
There is an explanation video available below.