Question

Some common changes are given below. Which of these changes doyou think can be reversed?

CHANGE	CAN BE REVERSED (YES or NO)
Raw egg to boiled egg
Batter to Idli
Wet clothes to dry clothes
Woolen yarn to knitted sweater
Grain to its flour
Cold milk to hot milk
Straight string to coiled string
Bud to flower
Milk to powder
Cow dung to biogas
Stretched rubber band to its normal size
Melting of Ice-cream

Answer 1

The changes which can be reversed means formation of starting reactant from product. There are some cases when any changes make new physical and chemical properties, in these cases there is no possibility that product will further changes to reactant from which it will make. So, these changes are non-reversible but when the reactant or starting substance is restored it will be called reversible change.

Complete step-by-step answer: In chemistry we read about changes, we read about systems where the process of change is taking place. Every substance has some physical and chemical properties. In a reaction when these physical and chemical properties change and a new substance is formed it is called as a non-reversible reaction or non-reversible change has taken place. In non-reversible change we never get the reactant substance after the change but in case of reversible change any how we can get the starting product.
So, among the options we have some changes which are reversible and some are not. Let’s start with raw egg which changes to boiled egg and we never get the raw egg at any cost. It is a non-reversible change. Next we have batter to idli, in this case we apply heat and make idli from its batter so it is also a non-reversible change. In case of wet clothes to dry clothes, we can make dry clothes wet by soaking them in water again so it is a reversed change. In case of woolen yarn to a knitted sweater, the sweater can be changed into woolen by just taking out the tread so yes it is also a reversed change. Grain to flour cannot be reversed, flour is obtained by crushing the wheat on the other hand cold milk and hot milk can be converted or reversed by just applying heat or revered by cooling it. Similarly, coiled string can be changed into straight chain string by applying force. Bud to flower is not a revered changed similarly paneer cannot be changed back to milk. Stretched rubber bands can be changed to its normal size. It is a revered change and melting of ice cream is also a revered change as we can freeze it again using a refrigerator. Conversion of biogas back to cow dung is not a revered change so we can easily fill up the table.

CHANGE	CAN BE REVERSED (YES or NO)
Raw egg to boiled egg	No
Batter to Idli	No
Wet clothes to dry clothes	Yes
Woolen yarn to knitted sweater	Yes
Grain to its flour	No
Cold milk to hot milk	Yes
Straight string to coiled string	Yes
Bud to flower	No
Milk to powder	No
Cow dung to biogas	No
Stretched rubber band to its normal size	Yes
Melting of Ice-cream	Yes

Note: You can take examples of conversion from your daily life that you can revere the process or not. In some cases chemical reactions or electrolysis take place to make the reaction reversible but most of the examples are from daily life so you can predict. You can say reversible and non-reversible processes also.