Question

Which of the following could be classified as producing a physical change?

A. Burning a candle
B. Leaving a bicycle outside to rust
C. Bending sheet metal
D. Toasting a slice of bread

Answer 1

D which is Toasting a slice of bread

Answer 2

C. Bending sheet metal.

Step-by-step explanation:

The metal is still intact. No change in chemical bonds have occurred.

Burning a candle is converting wax into heat, CO2 and carbon soot.

A rusting bicycle is converting goof iron, Fe, into iron oxide (rust, Fe2O3)

Toasting bread is more difficult to define. If the bread is just warmed, then it is physical. If it is toasted (browned/burned), then a few surface molecules have been converted into tasty carcinogens, my favorite poison.