Question

Which of the following is a physical change

A. Sawing a piece of wood in half
B. burning a piece of wood
C. rust forming on an iron fence
D. a copper roof changing color from red to green

Answer 1

A physical change would be A. Sawing a piece of wood in half because it's still the same. It would be a chemical reaction if the color of the wood would've changed.

Answer 2

Answer:-

• Sawing of piece of wood in half.

→ Physical; it is because no chemical properties are changed. They are same, just change is seen physically.

• Burning of a piece of wood.

→ Chemical; it is because chemical changes are observed. Wood is converted into Carbon.

• Rust forming on an iron fence.

→ Chemical; iron looses it's chemical properties on rusting. Thus, it is a chemical change.

• A copper roof changing color from red to green.

→ Chemical; chemical change is observed.

Conclusion: Sawing a piece of wood in half is the answer.