dioxide and monoxide

1)
There is acidic impurities in the iron, limestone(CaCO3)under strong heating,can change to Calcium oxide and cardon dioxide.CaCO3-----＞CaO+CO2
2)
佢錯，答案並不一定係正確的，話說香港的出書係為賺錢，而非為教育用途，所以d答案唔係太認真去校核對，以致有時出錯。carbon dioxide已經係CO2，唔可以再加Oxgen入去了(呢個reaction唔會出carbonate)。所以carbon monoxide先正確。除了Carbon可以reduce metal oxide，carbon momoxide,hydrogen可以。
3)carbon dioxide已經不能再react了，多數都係chemical equation的右方(product)，而carbon monoxide係可以被oxidize，變成carbon dioxide。

2008-03-24 21:15:47 補充：
CaO can neutralize the acidic impurities to prevent the iron reoxide into oxide by acid in high temperature .

2008-03-24 21:20:22 補充：
There is a chain reaction. carbon dioxide first react with
coke to form carbon monoxide. then carbon monoxide
react with the ore.
樓上係無錯。但你睇睇段文字，佢寫的對象係Iron(III)cide(Fe2O3)，唔係coke呢!!!
如果佢寫carbon dioxide react with coke to form carbon monoxide to reduce iron(III) oxide，那就正確了。而家係講CO2 reduceFe2O3，所以就錯了。

2008-03-24 21:21:01 補充：
Iron(III)cide(Fe2O3)-----＞Iron(III)oxide(Fe2O3)

2008-03-24 21:21:44 補充：
reoxide-----＞reoxdize

1. limestone may react with some impurities in the ore.
2. there is a chain reaction. carbon dioxide first react with
coke to form carbon monoxide. then carbon monoxide
react with the ore.
3. reduction of the ore requires carbon monoxide.
carbon monoxide is a reduction agent. but carbon dioxide
is not.