Question

Question 1

Which of the following is not an example of a chemical change?

A candle burning

Cake baking

Glass breaking

A nail rusting

Question 2

All of the following require breaking and forming chemical bonds except:

Freezing ice

A plant decaying

A piece of silver tarnishing

Roasting a marshmallow

Question 3 (Multiple Choice Worth 2 points)

Chemical changes

are only caused through burning a material.

only occur to weak materials.

change the identity of a substance.

do not affect the identity of a sub

Answer 1

i really need help!

Answer 2

i really need help!

Answer 3

Question 1:
Glass breaking - this is because only the appeareance of the glass changes, but the chemical composition does not.
Question 2:
Roasting a marshmallow (I think) since all the others require some sort of chemical bond change. I don't think a marshmallow does though.
Question 3:
Chemical change changes the identity of a substance. - new chemicals and elements occur and appear, so the original substance is changed into another one.

Answer 4

thanks!

Answer 5

#2 isn't a marshmallow.

In general, chemical and physical changes can be distinguished by asking if the change is "easy" to undo. Can you un-melt water? of course. Can you un-burn a marshmallow? didn't think so