Favourable and Unfavourable Change

Which condition must be true for a permanent change?

Mary lit an incense stick. She sensed a pleasant smell for as long as the stick was burning. The incense stick burnt up completely, leaving some ash behind.

What can be concluded from Mary’s activity?

A chick hatches out from an egg by breaking the eggshell.

Is the breaking of the eggshell a permanent change or a temporary change? Explain your answer.

Which of the following is irreversible reaction?

Why stretching of rubber band is considered as reversible change?

Why the burning of incense stick is considered as an irreversible change?

Compare the changes due to rolling roti from the dough and the cooking roti from the dough.

The conversion of rolled roti back into the ball of dough is a _____ change. 

Which of the following irreversible changes occur on their own?

Choose the right word and fill in the blank provided below.

When we heat water in a pan, it begins to boil after some time. If we continue to heat further, the quantity of water in the pan will _____. (decrease, increase)

Which of the following changes in our body are irreversible?

Identify the irreversible changes from the given options.

 Which of these options in which change around you takes place or involved?

Which of the following changes can be reversed?

Which of the following options indicate a 'reversible change'?

Which of the following changes are reversible, when a candle is burned?

An iron ring is heated. Which of the following statements about it is incorrect? 

Which of the following changes cannot be reversed? 

Let us conduct an activity to know that the air has weight.

Take a stick of $50$ cm length. Tie an air filled balloon to one of its ends and an empty balloon to the other end. Tie a thread at the exact center of the stick as shown in the picture and hold it freely. What do you observe? 

Why is cutting of an apple both a physical change and an irreversible one?