Page 65 - Science Class 06

CLASSIFICATION OF CHANGES are desired by all, while the harmful ones
We can classify changes in view of various
factors—speed, u lity, me-pa ern,
permanency, reversibility and the type of
reac ons.
Let us study various types of changes
according to the factors stated above:
SPEED
A change may takes place speedily, i.e.,
quite fast or tardily, i.e., quite slowly. So, in
view of speed, changes are of two
types—fast and slow.
Fast Changes
As the name suggests, these changes occur
sooner. For instance, a ba er turning into
pudding. It will take hardly a few minutes
for a liquid ba er to turn into a pudding.
Examples : ligh ng a match-s ck, a lightning
flash, blowing out of a candle, ligh ng an
electric bulb.
Burning of candle is an example
of fast change.
Slow Changes
These are the kinds of changes that will
happen over a period of me slowly. For
instance, a boy becoming a man is an
example of this as it happens over the years.
UTILITY
In terms of u lity, a change may be useful
for one and all or it may be harmful to all of
us. There is not denying that useful changes
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are not worth desiring. So, in view of u lity,
changes are of two types— desirable and
undesirable.
Desirable Changes
A desirable change is the one that is worth
desiring as it is good for all.
Examples : Growing up of a seedling into a
plant, change of milk into curd, conversion of
dung into manure, pasteurising of milk, etc.
Growing of plants is a desirable change.
Undesirable Changes
An undesirable change is the one that is no
worth desiring as it is not useful to all of us.
Examples : Going bad of food, ro ng of a
fruit, souring of milk, breaking of cap, etc.
Ro en food is an undesirable change.
1. How can you classify changes on the
basis of speed?
2. Give any two examples of changes which
are beneficial for man.
3. Give two examples of undesirable
changes.
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