WATER TECHNOLOGY

Hardness in water is caused by the presence of:

• Sodium chloride

• Sodium carbonate

• Calcium chloride

• Potassium nitrate

Permanent hardness in water is caused by the presence of:

• Calcium bicarbonate

• Magnesium sulfate

• Both of them

• None of them

Water is hard when it contains:

• Acid solution

• Precipitate in suspension

• Dissolved sodium salts

• Dissolved Ca and Mg salts

Soft water is water that;

• Does not lather
• Lathers with difficulty
• Lathers easily
• Does not form bubbles

If water contains calcium and hydrogen carbonate ions, it is described as....

• temporarily permanently soft water
• Soft water
• Permanently hard water
• Temporary hard water

If water contains calcium and sulphate ions, it is described as....

• temporarily permanently soft water
• Soft water
• Permanently hard water
• Temporary hard water

Which of the following does not cause the permanent hardness in water?

• Nitrates

• Sulphates

• Chlorides

• Bicarbonates

In _____________ when the water is heated then the soluble salts turns into insoluble ones and removed by filtration.

• Temporary hardness

• Permanent hardness

• Non-carbonate

• Non-alkaline

Scale formation in boilers causes

• no loss of heat

• wastage of heat

• increase in efficiency

• none of the above

Blow-down operation causes the removal of

• SCALES

• SLUDGES

• BOTH OF THESE

• HOT WATER ONLY