2. Hard water is water that has
high mineral content. Hard drinking
water is generally not harmful to one's
health, but can pose serious problems in
industrial settings, where water hardness
is monitored to avoid costly breakdowns
in boilers, cooling towers, and other
equipment that handles water. In
domestic settings, hard water is often
indicated by a lack of suds formation
when soap is agitated in water, and by
the formation of lime scale in kettles and
water heaters. Wherever water hardness
is a concern, water softening is
commonly used to reduce hard water's
adverse effects.

3. Water softening is the removal
of calcium, magnesium, and
certain other metal cations in hard
water. The resulting soft water is
more compatible with soap and
extends the lifetime of plumbing.
Water softening is usually achieved
using lime softening or ionexchange resins.

4. (a) By the use of soda:
Soda removes both temporary and permanent hardness. It is also
inexpensive and easy to use. This makes it the ideal substance for
softening water in the home.
(b) Other softening agents in the home:
It is difficult for the housewife to be very precise in the use of soda
and the water softened by soda may often contain an excess of
it, which even if it is slight, may damage certain fabrics. Hence, other
softening agents could be used. They are:
(i) Soap:
Soap is used as a softening agent. However, the use of soap as a
softening agent is extravagant on account of its high cost compared
with soda.