Answer. Temporary hardness is because of presence of bicarbonate s of calcium and magnesium.
Effects of hard water
(i) Hard water consumes large amount of soap in washing purposes.
(ii) Drinking hard water causes stomach disorders.
(iii) Hard water is unfit for use in steam engines, boilers and turbines because insoluble calcium and magnesium salts are deposited inside. Which is called scale? They are bad conductors of heat and hence more fuel is used. Insoluble calcium and magnesium sulphates not only reduce the efficiency of the engine but also cause the boiler to burst.