Older MCQs might not have the typical A, B, C,
D
choices. They
have choices 1, 2, 3, and a combination of them is the answer. Below is the key that maps such
combinations to the answer.
A
1, 2 and 3 are correct
B
1 and 2 only are correct
C
2 and 3 only are correct
D
1 only is correct
Describe the extraction of iron from hematite in the blast furnace, including symbol equations for each step, limited to: (a) the burning of carbon (coke) to provide heat and produce carbon dioxide (b) the reduction of carbon dioxide to carbon monoxide (c) the reduction of iron(III) oxide by carbon monoxide (d) the thermal decomposition of calcium carbonate/limestone to produce calcium oxide (e) the formation of slag
Describe how the greenhouse gases carbon dioxide and methane cause global warming, limited to: (a) the absorption, reflection and emission of thermal energy (b) reducing thermal energy loss to space
State the sources of the sulfur dioxide (burning sulfur or roasting sulfide ores) and oxygen (air) in the Contact process
