Finding difficulties in memorizing things? Let's learn it in some easy ways.

Trick to Remember Causes of Permanent Hardness - PCS 
To remember the chemicals that cause permanent hardness, simply remember the abbreviation - PCS (or you can read it as 'Picks'). 
P - Permanent hardness 
C - Chloride of magnesium and calcium 
S - Sulfate of magnesium and calcium

Trick to Remember Causes of Temporary Hardness - TB 
To remember the chemicals that cause permanent hardness, simply remember the abbreviation - TB (or you can read it as 'Tub'). 
T - Temporary hardness 
B - Bicarbonate of magnesium and calcium

Trick to Identify Hard and Soft Water 
To identify if a particular sample of water is hard or soft water, mix it with soap in a bottle and shake it. If there are lots of bubbles and the water remains clear, it's soft water. If there are no bubbles and the water is cloudy, it's hard water. Simple?

Hydrogen