Physical and Chemical Changes

The banana is yellow.

• intensive physical property

• extensive physical property

Answer explanation

The color of a banana, being yellow, is an intensive physical property. Intensive properties do not depend on the amount of substance, while extensive properties do. Therefore, the correct choice is 'intensive physical property'.

What are some things you could do to a banana that would be a physical change?

• Cut the banana

• Break it apart

• Smoosh it

• Let it ripen

Answer explanation

Cutting, breaking, or smooshing a banana are all physical changes because they alter its shape and form without changing its chemical composition. Letting it ripen is a chemical change, as it affects the fruit's internal structure.

Why is chopping firewood a physical change?

• It changes the size and shape of the wood.

• Chopping wood does not change its chemical composition.

• It changes the form of the wood.

• All of the above.

Answer explanation

Chopping firewood is a physical change because it alters the size and shape of the wood, changes its form, and does not affect its chemical composition. Therefore, all the provided statements are correct.

The chocolate is brown.

• intensive physical property

• extensive physical property

Answer explanation

The chocolate's color, brown, is an intensive physical property because it does not depend on the amount of chocolate present. Extensive properties, like mass or volume, vary with the quantity.

The chocolate bar is 3 cm long.

• intensive physical property

• extensive property

Answer explanation

The length of the chocolate bar, 3 cm, is an extensive property because it depends on the amount of material present. Intensive properties, like density, do not change with the size or amount of substance.

Burning is a...

• Physical Change

• Chemical Change

Answer explanation

Burning is a chemical change because it involves a reaction that transforms substances into new products, releasing energy in the form of heat and light, unlike physical changes that do not alter the chemical composition.

Why is boiling water a physical change?

• • It undergoes a phase transition from a liquid to a gas without any alteration in its chemical composition.

• • There is no breaking or formation of chemical bonds during the process.

• • The process is reversible, and liquid water can be obtained back by cooling the vapors.

• None of the above (Boiling Water is a Chemical Change)

Answer explanation

Boiling water is a physical change because it transitions from liquid to gas without changing its chemical composition, no chemical bonds are broken or formed, and it can be reversed by cooling the vapor back to liquid.

Rusting is a physical change?

• True

• False

Answer explanation

Rusting is a chemical change, not a physical one, as it involves the reaction of iron with oxygen and moisture to form iron oxide. Therefore, the statement that rusting is a physical change is false.

How do you know rusting is a chemical change?

• There is a change in the shape of the object.

• There is a change in the color of the object.

• The chemical composition is not altered.

• What's a chemical change?

Answer explanation

Rusting involves a change in color, typically from metallic to reddish-brown due to iron oxide formation. This indicates a chemical change, as the original material's properties and composition are altered.

• Which one of the following is NOT a physical property of a log?

• • A log can be made into toothpicks

• • A log can be digested by a beaver

• • A log can be split with an axe

• • A log is heavy

Answer explanation

The correct choice is 'A log can be digested by a beaver' because this describes a biological interaction, not a physical property. The other options describe physical characteristics or uses of a log.