Chemical Changes and Reactions Quiz

Which of the following best describes a chemical change?

• A change in which no new substances are formed

• A change that is usually reversible

• A change in which new substances are formed

• A change that always involves the absorption of heat

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

• Burning of wood

• Rusting of iron

• Dissolving sugar in water

• Cooking an egg

What are the reactants in a chemical reaction?

• The substances formed after the reaction

• The substances that take part in the reaction

• The substances that are always metals

• The substances that can be separated using filtration

Why is burning a piece of paper considered a chemical change?

• It can be easily reversed

• It produces new substances such as ash and gases

• The paper remains the same but changes shape

• The process only involves a change of state

Which of the following statements about chemical changes is false?

• Chemical changes usually involve the formation of new substances

• Chemical changes are usually difficult to reverse

• Energy may be taken in or given out during chemical changes

• The reactants and products in a chemical change are always identical

In a word equation, where are the reactants and products placed?

• Reactants on the right, products on the left

• Reactants on the left, products on the right

• Reactants and products can be placed in any order

• Reactants are always written below the arrow

What does the arrow in a word equation represent?

• It separates elements and compounds

• It shows the reactants being destroyed

• It represents the formation of new substances

• It indicates the reaction is reversible

Which of the following is an example of a correct word equation?

• Oxygen + Carbon → Carbon dioxide

• Hydrogen + Water → Oxygen

• Carbon dioxide → Carbon + Oxygen

• Water → Hydrogen + Nitrogen

Why is mass conserved in a chemical reaction?

• Because new atoms are created during the reaction

• Because atoms are rearranged but not created or destroyed

• Because some atoms disappear after reacting

• Because reactants and products are always identical

Which of the following best describes a chemical reaction?

• The number of atoms before and after the reaction is different

• The number of each type of atom remains the same before and after the reaction

• The reactants and products are always the same substances

• Mass is lost during the reaction