Question

classify each of the following as a physical change or property, or a chemical change or property
a) oven cleaners contain sodium hydroxide, which converts the grease/oil soathers inside the oven to water soluble materials, which can be washed away.
b) a rubber band stretches when you pull on it.
c) a cast iron frying pan will rust if it is not dried after washing.
d) concentrated hydrochloric acid has a choking, pungent odor.
e) concentrated hydrochloric acid will burn a hole in cotton jeans because the acid breaks down the cellulose fibers in cotton.
f) copper compounds often form beautiful blue crystals when a solution of a given copper compound is evaporated slowly.
g) copper metal combines with substances in the air to form a green \patina\ that protects the copper from further reaction.
h) bread turns brown when you heat it in the toaster.
i) when you use the perfume your boyfriend gave you for your birthday, the liquid of the perfume evaporates quickly from your skin.
j) if you leave your steak on the gas grill too long, the steak will turn black and char.
k) hydrogen peroxide fizzes when it is applied to a cut or scrape.

Explanation:

To solve this, we classify each as physical/chemical change or property by checking for new substances (chemical) or just state/appearance change (physical):

a)

*: Oven cleaners having NaOH (converts grease) describes a chemical property* (ability to react, forming new substances).

*: Water-soluble materials being washable describes a physical property* (no new substance, just solubility).

*: Rubber stretching (no new substance) is a physical property* (elasticity, a physical characteristic).

Answer:

**: Chemical Property

b)