Chem and Phys changes ++

Mark is observing a burning candle.  He notices that the candle wax makes a pool and dribbles down the side of the candle, where it hardens again.  The wax has undergone:

• a physical change

• a chemical change

• a physical and chemical change

• the formation of a new substance

A different chemical substance is formed when

• a cloth is cut

• a cup breaks

• a candle burns

• a piece of chalk falls apart

Which object would be most likely to rust?

• an iron nail

• a plastic comb

• a glass marble

• a paper cup

David added a little baking soda to a beaker that contained vinegar.  Bubbles started coming from the mixture and a gas was released.  The gas was evidence that:

• the mixture was starting to boil.

• the air in the flask contracted.

• the vinegar and baking soda expanded.

• a chemical reaction took place.

An example of a liquid turning into a gas is:

• a chocolate bar melting

• steam escaping from a cup of hot chocolate

• an ice cream cone dripping

• a stick of butter getting warm

If you dissolved a lot of salt in some water in a large, flat dish and put the dish in bright sunlight on a hot day, what would be left in the dish after a long time?

• dry salt

• water with no salt

• the same salty water as before

• nothing

How do we know if it is a chemical change?

• can be undone
• cannot be undone
• both
• none

Physical changes size and shape of something?

• False
• True

Ice can be a physical change?

• False
• True

When something new is created or a substance is broken down into diffrent chemicals, you have a chemical change.

• True
• False