Which of the following would be considered a chemical change ?
I. Frost forms on the window
II. A Silver fork tarnishes
III. Toasting a slice of bread.

Question

Quizplus · Accepted Answer

I is a physical change because frost is just water vapor that has turned into ice on the surface of the window. 
II is a chemical change because silver tarnishing is a result of a chemical reaction with sulfur compounds in the air. 
III is also a chemical change because toasting bread causes a chemical reaction where the heat transforms the bread's starches and sugars into a crusted, browned layer. Thus, only II and III involve a chemical change.

Which of the Following Would Be Considered a Chemical Change