Question

1. butter melts and burns in a hot frying pan. which of these changes is physical and which is chemical? explain.

Explanation:

• Melting of butter: A physical change. When butter melts in a hot frying pan, it changes from a solid to a liquid state. This is a physical change because the chemical composition of butter (the molecules of fat, etc.) remains the same. The change is only in the physical state (from solid to liquid) and can be reversed (by cooling the melted butter, it will solidify again).
• Burning of butter: A chemical change. When butter burns, it reacts with oxygen in the air. This reaction causes the butter to break down into new substances (like carbon, water vapor, and other combustion products). The chemical composition of butter is altered, and this change is irreversible (you cannot get the original butter back from the burnt residue).

Answer:

• Melting of butter is a physical change (as it involves a change in state without altering the chemical composition of butter).
• Burning of butter is a chemical change (as it involves a reaction with oxygen, forming new substances and altering the chemical composition of butter).