Science
see also GCSE
Geography page
Water Filters

Hard and soft water
The label on a bottle of mineral water listed the following information:

Ions present
Concentration in mg per litre
calcium
75
magnesium
25
sodium
12
potassium
2
hydrogencarbonate
370
sulfate
6
chloride
6
Click on the name of the compound which causes temporary hardness in the mineral water.
A) magnesium sulfate
B) sodium chloride
C) calcium hydrogencarbonate
D) potassium chloride
Permanent hardness is caused by the presence of ?
A) potassium sulfate
B) calcium hydrogencarbonate
C) calcium sulfate
D) sodium carbonate



In an investigation of hard water, soap solution was added to water samples from four sources until a lather formed. Further samples were then boiled and tested again.

Source
Volume of soap solution added (ml)
Volume of soap solution added after boiling (ml)
Distilled water
0.5
0.5
A
5.0
4.0
B
3.5
0.5
C
2.0
2.0

Click on buttons to show which of the statements below are TRUE and which are FALSE

Sample C contains only permanent hardness
True
False
Sample B contains both temporary and permanent hardness
True
False
There is permanent hardness in samples A and C
True
False
Sample A contains both temporary and permanent hardness
True
False
There is permanent hardness in samples A and B
True
False
Sample B contains only temporary hardness
True
False
There is temporary hardness in samples A and B
True
False