Iron is obtained from the ore haematite in a blast furnace. Which statement about this extraction method is correct?
- AAir is blown into the blast furnace to react with carbon.
- BAt the bottom of a blast furnace a layer of molten iron floats on top of a layer of molten slag.
- CLimestone is decomposed in the blast furnace to produce carbon monoxide.
- DSilicon dioxide, an impurity in the ore, is a basic oxide.