Water (H₂O) is made of (contains) ________ and ___________.

• Hydrogen and oxygen
• carbon and oxygen
• hydrogen and carbon
• no elements

7.Your friend decides to toast a piece of bread, but leaves it in the toaster too long. The bread is black and the kitchen if full of smoke.

• physical change
• chemical change

In a fireworks show, the fireworks explode giving off heat and light.

• physical change
• chemical change

Which of the following tells you that a chemical change may have occurred?

• change shape
• melting
• bubbles forming
• freezing

12. What happens in ALL chemical changes?

• change in state of matter
• bubbles are produced
• a new substance is formed/atoms rearrange
• nothing

Which of the following IS a clue that a chemical change has occurred?

• state of matter change
• change in temperature
• size change
• shape change

What helps us to identify substances?

• Sherlock Holmes
• combining them with metals
• properly writing lab reports
• observing their properties

If there is a change in color, production of light, production of heat, production of gas, production of smell or formation of a new substance.

• physical change
• chemical change

Which of the following is an example of a physical change?

• Baking a cake

• Rusting iron

• Burning wood

• Melting ice

What is the main difference between a physical and a chemical change?

• Physical changes create new substances

• Chemical changes are reversible

• Chemical changes involve the rearrangement of atoms

• Physical changes involve the rearrangement of atoms