Chemical Reactions and Changes 2025-26

What is a physical change?

• A change that produces a new substance

• A change that is often reversible

• A change that involves breaking chemical bonds

• A change that results in a temperature change

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

• Melting ice

• Burning wood

• Sanding wood

• Heating metal

What happens to the chemical structure of water when it changes from ice to steam?

• It changes completely

• It remains the same

• It forms new molecules

• It becomes a new substance

What is a common indicator of a chemical reaction?

• Change in shape

• Change in texture

• Change in color

• Change in state

What is formed when iron reacts with oxygen?

• Iron chloride

• Iron oxide

• Iron sulfide

• Iron nitrate

What does the formation of a precipitate indicate?

• A physical change

• A chemical reaction

• A change in state

• A reversible change

What gas is released when vinegar and baking soda are mixed?

• Oxygen

• Hydrogen

• Carbon dioxide

• Nitrogen

What happens to table salt when it is dissolved in water?

• It forms a new substance

• It chemically reacts with water

• It dissociates into ions

• It becomes permanently altered

What is an alloy?

• A chemical compound

• A mixture of metals

• A new substance formed by a chemical reaction

• A reversible change

What is brass made of?

• Copper and tin

• Copper and zinc

• Iron and carbon

• Aluminum and magnesium