Question

match the example with the type of change
rusting metal
broken pencil
fire
boiling water
hair cut
digesting food
chemical change
physical change

Explanation:

• Rusting Metal: Rusting is a chemical reaction where metal (e.g., iron) reacts with oxygen and moisture to form a new substance (rust, like iron oxide). So it is a chemical change.
• Broken Pencil: Breaking a pencil only changes its physical form (size, shape). No new substances are formed. So it is a physical change.
• Fire: Fire involves a chemical reaction (combustion). For example, when wood burns, it reacts with oxygen to form new substances like carbon dioxide, ash etc. So it is a chemical change.
• Boiling Water: Boiling water changes its state from liquid to gas (water vapor). It is a physical change as the chemical composition of water (\(H_2O\)) remains the same.
• Hair Cut: Cutting hair only changes the physical appearance (length of hair). No new chemical substances are formed. So it is a physical change.
• Digesting food: Digestion involves chemical reactions. Enzymes break down complex food molecules (like proteins, carbohydrates) into simpler substances (amino - acids, glucose etc.). So it is a chemical change.

Answer:

• Chemical change: Rusting Metal, Fire, Digesting food
• Physical change: Broken Pencil, Boiling Water, Hair Cut