S2 chemistry - Chemical Reactions

What is a sign of a chemical reaction?

• Color change

• Formation of a solid

• Release of gas

• All of the above

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

• Melting ice

• Boiling water

• Rusting iron

• Freezing water

What happens to the bonds in molecules during a chemical reaction?

• They are broken and new bonds are formed

• They remain the same

• They are replaced with new elements

• No bonds are involved

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

• Burning paper

• Dissolving salt in water

• Cooking an egg

• Rusting of iron

What effect does increasing temperature have on the rate of a chemical reaction?

• Slows it down

• Speeds it up

• No effect

• Stops the reaction

How does concentration affect the rate of reaction?

• Higher concentration increases the rate

• Higher concentration decreases the rate

• No effect

• Stops the reaction

What role do catalysts play in a chemical reaction?

• They increase the reaction rate

• They decrease the reaction rate

• They prevent reactions from occurring

• They change the products

Which factor does NOT affect the rate of a chemical reaction?

• Temperature

• Pressure

• Shape of the container

• Concentration

What is a common use of a catalyst in everyday life?

• To slow down a reaction

• To speed up a reaction

• To stop a reaction

• To increase temperature

What is an example of a biological catalyst?

• Enzyme

• Acid

• Base

• Salt