Chemical Reactions OCR KS3 Y8

Which of these is a chemical change?

• Iron rusting

• Water freezing

• Ice melting

• Glass breaking

Which of the following is a physical change?

• Boiling water

• Burning wood

• Baking a cake

• Cooking an egg

What is produced during complete combustion of a hydrocarbon?

• Carbon dioxide and water

• Carbon and water

• Carbon monoxide and steam

• Methane and carbon dioxide

What is required for combustion to occur?

• Oxygen

• Water

• Carbon dioxide

• Nitrogen

What does the word 'exothermic' mean?

• Gives out heat

• Takes in heat

• Breaks down molecules

• Changes colour

What type of reaction is respiration?

• Exothermic

• Endothermic

• Neutralisation

• Precipitation

Where does respiration occur in the body?

• In cells
• In the stomach.

• In the lungs.

• In the heart.

Which gas is produced during fermentation?

• Carbon dioxide

• Oxygen

• Hydrogen

• Nitrogen

What substance is made during fermentation of glucose by yeast?

• Ethanol

• Oxygen

• Carbon

• Lactic acid

What does the law of conservation of mass state?

• Mass is not lost or gained in a chemical reaction

• Atoms can be created

• Reactions always produce less mass

• Heat is always absorbed