HOT QUESTION: THINK AND ANSWER:
1) Tearing of paper is irreversible. It is, therefore , a chemical change. Do you agree? Give reasons.
2) A potato remains a potato even after it is cooked. Therefore, cooking is a physical change. Do you agree? Give reasons.
3) When sugar dissolves in water, it disappears. That means it must have changed into a new substance. Therefore, dissolving is chemical change. Do you agree? Give reasons.
1) Tearing of paper is an irreversible change but after tearing its chemical composition does not change, hence it is not a chemical change.
2) Cooking of food is chemical change because it changes the chemical composition of the substance we are cooking.
3) When sugar dissolves in water then no chemical change takes place, because sugar is particulate in nature and when we add it to water then it gets divided into its particles and escape into the intermolecular spaces between the water molecules. That is the reason they disappear after dissolving.