$CATEGORY: Science - Khan Academy/3.Metals and Non-metals/3.Metals and Non-metals--Occurence of Metals

//Multiple Choice

What is roasting?  
{  
~Heating an ore in the absence of air  
=Heating an ore in the presence of excess air  
~Cooling an ore in water  
~Heating an ore with carbon  
}  

Which type of ore is generally concentrated by roasting?  
{  
~Carbonates  
=Sulphides  
~Oxides  
~Chlorides  
}  

What is calcination?  
{  
=Heating an ore in the absence of air  
~Heating an ore in the presence of excess air  
~Melting the ore  
~Adding flux to the ore  
}  

Which type of ore is concentrated by calcination?  
{  
~Sulphides  
=Carbonates  
~Chlorides  
~Nitrates  
}  

What is the main purpose of roasting?  
{  
~To remove moisture  
=To convert sulphides into oxides  
~To add flux  
~To melt the ore  
}  

Which gas is released during the roasting of sulphide ores?  
{  
~Carbon dioxide  
=Sulphur dioxide  
~Oxygen  
~Hydrogen  
}  

Which of the following is an example of calcination?  
{  
=CaCO3 → CaO + CO2  
~2ZnS + 3O2 → 2ZnO + 2SO2  
~2Fe2O3 + 3C → 4Fe + 3CO2  
~Al2O3 + 2NaOH → 2NaAlO2 + H2O  
}  

Why is calcination done in the absence of air?  
{  
=To prevent oxidation of the ore  
~To remove sulphur  
~To remove carbon  
~To add flux  
}  

Which of the following is an example of roasting?  
{  
=2PbS + 3O2 → 2PbO + 2SO2  
~ZnCO3 → ZnO + CO2  
~Fe2O3 + 3CO → 2Fe + 3CO2  
~NaCl + H2SO4 → NaHSO4 + HCl  
}  

What happens to volatile impurities during calcination?  
{  
~They are reduced to metal  
~They are converted to slag  
=They are removed as gases  
~They remain in the ore  
}  


//True or False

Roasting is done in the presence of air. {T}

Calcination is used to convert sulphide ores into oxides. {F}

Sulphur dioxide gas is released during roasting of sulphide ores. {T}

Calcination involves heating the ore in the presence of excess air. {F}

Both roasting and calcination result in the formation of oxides. {T}

Roasting is commonly used for carbonate ores. {F}

The reaction is an example of roasting. {F}

Roasting helps in the removal of moisture and volatile impurities. {T}

Calcination is performed to remove sulphur from sulphide ores. {F}

Both roasting and calcination are steps in the extraction of metals from ores. {T}


//Fill in the blanks

Roasting is the process of heating an ore in the presence of ________.  
{  
~Water  
=Air  
~Carbon  
~Hydrogen  
}  

Calcination is carried out in the ________ of air.  
{  
=Absence  
~Presence  
~Excess  
~Partial  
}  

During roasting, sulphide ores are converted into ________.  
{  
~Carbonates  
=Oxides  
~Chlorides  
~Nitrates  
}  

The gas released during the roasting of zinc sulphide is ________.  
{  
~Carbon dioxide  
=Sulphur dioxide  
~Oxygen  
~Hydrogen  
}  

Calcination is used to convert carbonate ores into ________.  
{  
~Sulphides  
=Oxides  
~Nitrates  
~Chlorides  
}  

An example of roasting is the conversion of ________ to zinc oxide.  
{  
~Zinc carbonate  
=Zinc sulphide  
~Zinc chloride  
~Zinc nitrate  
}  

In calcination, volatile impurities are removed as ________.  
{  
~Liquid  
=Gases  
~Solid slag  
~Oxides  
}  

The chemical reaction represents ________.  
{  
=Roasting  
~Calcination  
~Reduction  
~Refining  
}  

The reaction is an example of ________.  
{  
~Roasting  
=Calcination  
~Electrolysis  
~Smelting  
}  

The main purpose of roasting is to remove ________ from the ore.  
{  
~Carbon dioxide  
=Sulphur  
~Water  
~Oxygen  
}  


//Numericals

How much oxygen (in moles) is required to roast 1 mole of ZnS?  
{  
~1 mole  
=1.5 moles  
~2 moles  
~3 moles  
}  

Calculate the mass of SO2 produced when 97 g of ZnS is roasted.  
{  
~64 g  
=128 g  
~32 g  
~96 g  
}  

In the reaction, CaCO3 → CaO + CO2, how many grams of CO2 are released when 100 g of CaCO3 decomposes?  
{  
=44 g  
~50 g  
~22 g  
~88 g  
}  

If 2 moles of PbS are roasted, how many moles of SO2 are produced?  
{  
~1 mole  
=2 moles  
~3 moles  
~4 moles  
}  

How much oxygen (in grams) is needed to roast 1 mole of FeS?  
{  
~28 g  
=56 g  
~112 g  
~224 g  
}  

What is the mass of ZnO formed when 97 g of ZnS is roasted?  
{  
=81 g  
~97 g  
~162 g  
~64 g  
}  

How many grams are released when 50 g of CaCO3 is calcined?  
{  
=22 g  
~44 g  
~11 g  
~33 g  
}  

During the roasting of Cu2S, how many moles of SO2 are released if 1 mole of Cu2S is roasted?  
{  
~0.5 mole  
=1 mole  
~1.5 moles  
~2 moles  
}  

If 200 g of ZnCO3 is calcined, what is the mass of ZnO produced?  
{  
~81 g  
=129.6 g  
~162 g  
~108 g  
}  

How many grams of O2 are required to roast 150 g of ZnS?  
{  
~48 g  
=75 g  
~50 g  
~60 g  
}  


//Match the following

Match the following items from Column A with their correct corresponding options from Column B\:
{  
=Roasting -> Presence of air  
=Calcination -> Absence of air  
=Sulphide ores -> Presence of air  
=Carbonates ores -> Heating to remove CO2  
}  


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