You are here
What is a Desirable Change?
It means a change that is useful for us.
We want this change to happen.
What is an Undesirable Change?
It means a change that is harmful or wasteful for us.
We do not want this change to happen.
Examples of Desirable and Undesirable Changes
Desirable
↓
- Milk turning into curd
- Ripening of fruits
- Cooking of food
- Cutting of fruits
- Baking of bread
Undesirable
↓
- Rusting of iron tools
- Decay of food during storage
- Spoilage of milk
The Same Change Can Be Both
Sometimes, the same change is desirable in one situation and undesirable in another.
Example — decomposition of food
-
Undesirable:
when food decays in your kitchen.
- You wanted to eat that food.
- It has now gone to waste.
-
Desirable:
when food waste is decomposed into
compost
.
- The compost enriches the soil.
- It helps plants grow.
- So whether a change is desirable depends on the situation .
Quick fact: A change is "desirable" or "undesirable" based on what we want from it — not based on the chemistry. Composting is the same chemical decomposition as food spoilage; only the context is different.
Long-Term Environmental Changes
Some changes happen slowly over many years.
Their effects build up over time and can harm the environment.
Examples of slow harmful changes
-
Burning fuels:
in vehicles, factories, and aircraft.
- This releases carbon dioxide into the atmosphere.
- Carbon dioxide levels rise over the years.
-
Drying of paint:
on walls, doors, and furniture.
- It releases many substances into the air.
- This causes atmospheric pollution.
These are everyday chemical changes whose cumulative effect can be undesirable for the planet.
🤔
Quick Check — Test Yourself
-
Give two examples of desirable changes from daily life.
View Answer
(Any two) Milk turning into curd; ripening of fruits; cooking of food; baking of bread. -
Give two examples of undesirable changes.
View Answer
(Any two) Rusting of iron; decay of food; spoilage of milk. -
How is decomposition both desirable and undesirable?
View Answer
Undesirable when food spoils in your kitchen; desirable when food waste becomes compost for the soil. -
Name one change that pollutes the atmosphere.
View Answer
Burning of fuels in vehicles (releases carbon dioxide), or drying of paint (releases volatile substances). -
Why does the same change get classified differently in different situations?
View Answer
Because "desirable" and "undesirable" depend on what we want from the change — not on the chemistry of the change itself.
