Desirable and undesirable changes

Desirable and undesirable changes
§§ Desirable change:
        A change brought about by a person (or) the nature, which is useful, is called a desirable change. 
Desirable change should be:
        a.Changes that are not harmful or toxic or any living organisms.
        b.Changes that are beneficial to all organisms are termed desirable changes.
    Examples:    
        1) Formation of curd from milk is a desirable change. It is because curd is more easily digestible as compared to milk.
        2) Germination of seeds.
        3) Change of weather from winter to summer is a desirable change.
    §§ Undesirable change:
        A change brought about by a person (or) the nature, such that it has harmful effects is called an undesirable change.
    Examples:
        1) Food turning bad in summer is an undesirable change.
        2) Breaking of glass ware/glass article is an undesirable change.
        3) Rusting of articles of iron is an undesirable change.
        4) Global warming
        5) Rotting of fruits & vegetables
Note:
1. A change may be beneficial at one moment but unfavourable at another.
The burning of fuel (wood, coal) to generate heat is the desired change.
When a house or a factory is burned, it causes an unfavourable change.
2. For some, a change may be beneficial, but it may be destructive for others.
Cutting trees may be desirable for those who require wood, but it is undesirable for animals and the environment since it disrupts the natural equilibrium.