Chemical Reactions and Properties

What are the halogens?

• Sodium, Potassium, Calcium, Magnesium

• Carbon, Sulfur, Phosphorus, Selenium

• Hydrogen, Oxygen, Nitrogen, Argon

• Fluorine, Chlorine, Bromine, Iodine, Astatine

Which of the following is a physical property?

• Color

• Rusting

• Reactivity with another substance

• Combustion

What color is Chlorine gas?

• Green

• Dark grey

• Pale yellow

• Red-brown

What happens to the color of halogens as you go down the group?

• They disappear

• They remain the same

• They become darker

• They become lighter

Which gas makes up approximately 21% of the air?

• Nitrogen

• Oxygen

• Argon

• Carbon Dioxide

What is the main method to determine the percentage of oxygen in the air?

• Using a thermometer

• Counting gas molecules

• Reacting air with iron or phosphorus

• Measuring temperature

What is combustion?

• A reaction with water

• A reaction with oxygen

• A reaction with acids

• A reaction with bases

What is the balanced equation for the combustion of hydrogen?

• H₂ + O₂ → H₂O

• 2H + O → H₂O

• 2H₂ + O₂ → 2H₂O

• H₂ + O₂ → 2H₂O

What is thermal decomposition?

• Combining substances

• Breaking down a compound using heat

• A type of combustion

• A method of rust prevention

How does increasing carbon dioxide levels contribute to climate change?

• It increases oxygen levels

• It traps heat in the atmosphere

• It decreases humidity

• It cools the atmosphere