Exploring Chemical Reactions: Reactants and Products

Why are chemical reactions crucial for life and the universe?

• They allow the formation and breaking of bonds between atoms or molecules.

• They create new elements.

• They stop the universe from expanding.

• They prevent the existence of life.

What are the reactants in the formation of water?

• Molecular oxygen and nitrogen

• Molecular hydrogen and nitrogen

• Molecular hydrogen and carbon dioxide

• Molecular hydrogen and molecular oxygen

How many molecules of molecular hydrogen are needed for the reaction to form water?

• Three

• Four

• Two

• One

What is produced when molecular hydrogen reacts with molecular oxygen?

• Water

• Methane

• Carbon dioxide

• Nitrogen

Why is energy important in chemical reactions?

• It makes molecules heavier.

• It helps molecules to bounce around and collide in the right ways.

• It cools down the reactants.

• It stops the reaction from happening.

What is the difference between a molecule and a compound?

• A molecule is made up of one element, while a compound is made up of two or more different elements.

• A molecule is always larger than a compound.

• A compound is made up of one element, while a molecule is made up of two or more different elements.

• There is no difference between a molecule and a compound.

Which of the following is an example of a compound?

• Helium

• Water

• Molecular oxygen

• Molecular hydrogen

What does an irreversible reaction imply?

• The reaction can easily go both ways.

• The reaction is very unlikely to go the other way.

• The reaction does not produce any products.

• The reaction does not require any energy.

What is an ion?

• A molecule or atom with a balanced number of electrons and protons.

• A molecule or atom that is always neutral.

• A molecule or atom with an imbalance of electrons or protons causing a net charge.

• A molecule or atom that does not react.

What happens in a reversible reaction?

• The reaction stops after forming products.

• The reaction does not involve any energy.

• The reaction only goes in one direction.

• The reaction can go back and forth between reactants and products.