Understanding Physical and Chemical Changes

What is a key characteristic of a physical change?

• Change in state without altering identity

• Production of gas

• Change in color

• Formation of a new substance

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

• Breaking glass

• Burning wood

• Melting ice

• Dissolving sugar in water

What happens when hydrogen gas reacts with oxygen gas?

• They form hydrogen peroxide

• They remain unchanged

• They form a mixture

• They form water, a new substance

Which property can only be observed by changing the substance's identity?

• Color

• Flammability

• Melting point

• Density

What is a sign that a chemical change has occurred?

• The substance dissolves

• A new color appears

• The substance is heated

• The substance is mixed

Which of the following is NOT a sign of a chemical change?

• Change in odor

• Formation of a precipitate

• Change in temperature

• Change in shape

What is the only way to be sure a chemical change has occurred?

• Observing a color change

• Testing for a new substance

• Noticing a temperature change

• Smelling a new odor

What happens when magnesium reacts with oxygen?

• It forms a new substance

• It remains unchanged

• It melts

• It becomes magnetic

What is produced when magnesium is corroded by acids?

• Nitrogen gas

• Carbon dioxide

• Hydrogen gas

• Oxygen gas

Which of the following is a chemical property of magnesium?

• It has a high melting point

• It is not magnetic

• It is a solid at room temperature

• It combusts with oxygen