The Limestone Cycle

What is the chemical name for limestone?

• Calcium hydroxide

• Calcium carbonate

• Calcium oxide

• Carbon dioxide

When limestone is heated strongly, it decomposes to form:

• Calcium hydroxide and carbon dioxide

• Calcium carbonate and water

• Calcium oxide and carbon dioxide

• Calcium chloride and water

What is the common name for calcium oxide?

• Quicklime

• Slaked lime

• Chalk

• Marble

When water is added to calcium oxide, it produces:

• Calcium carbonate

• Calcium hydroxide

• Calcium chloride

• Calcium sulfate

What is the common name for calcium hydroxide?

• Quicklime

• Slaked lime

• Limestone

• Limewater

When limestone (CaCO₃) is heated strongly, it breaks down into simpler substances. Which of the following equations shows this reaction?

• Ca(OH)₂ → CaO + H₂O

• CaCO₃ → CaO + CO₂

• CaO + CO₂ → CaCO₃

• CaCO₃ + H₂O → Ca(OH)₂

What happens when carbon dioxide is bubbled through limewater?

• It turns purple

• It turns clear

• It turns milky

• It fizzes

The milky appearance in limewater is caused by:

• Calcium carbonate forming

• Calcium hydroxide dissolving

• Carbon dioxide escaping

• Hydrogen being released

Which of the following shows the correct order in the limestone cycle?

• Calcium carbonate → Calcium hydroxide → Calcium oxide

• Calcium carbonate → Calcium oxide → Calcium hydroxide → Calcium carbonate

• Calcium hydroxide → Calcium oxide → Calcium carbonate

• Calcium oxide → Calcium carbonate → Calcium hydroxide

Which of the following correctly describes the test for carbon dioxide?

• Bubble the gas through limewater – it turns milky

• Light a splint – it pops

• Use damp red litmus – it turns blue

• Add acid – it fizzes