7. Analysing the changes

 

 As Riya helps her mother prepare dinner, she chops vegetables into small pieces before cooking them with spices to make a curry. Her younger brother argues that both activities are the same type of change because the vegetables look different after each one.

Do you agree with his statement? Explain the type of change involved in both activities with reasons.

 

I do not agree with Riya's younger brother because the two activities involve different types of changes.

 

Cutting vegetables is a physical changeoxidation processcombustion reactionchemical change because a new substance is formedonly the size and shape changeonly the colour changesonly the smell changes. The vegetables remain the same substances, and a new substance is formedash is producedno new substance is formedcarbon dioxide is produced.

 

Cooking vegetables is a temporary changechemical changestate changephysical change because new substances with different properties are formedonly the shape changesonly the state changesthe original substance remains unchanged. The cooked vegetables have a different taste, smell, texture, and cannot be changed back into raw vegetables easily.

 

Therefore, cutting vegetables is a physical change, whereas cooking vegetables is a chemical change because only physical properties change in the first activity, while a new substance is formed in the second activity.