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

//Multiple Choice

Which process is used to extract metals at the top of the reactivity series?
{
~ Reduction with carbon
= Electrolysis
~ Froth flotation
~ Roasting
}

The extraction of moderately reactive metals like zinc from their ores is done by\:
{
= Reduction with carbon
~ Electrolysis
~ Froth flotation
~ Smelting
}

Which of the following is an ore of iron?
{
~ Bauxite
= Hematite
~ Malachite
~ Galena
}

In the extraction of aluminum, cryolite is used to\:
{
~ Increase the melting point of aluminum oxide
= Lower the melting point of aluminum oxide
~ Reduce aluminum oxide
~ React with impurities
}

What is gangue in metallurgy?
{
~ The pure metal extracted
= The impurities associated with the ore
~ The reducing agent
~ The flux added during extraction
}

//True or False

Carbon is used as a reducing agent to extract metals like iron and zinc. {T}

Metals at the bottom of the reactivity series are extracted by electrolysis. {T}

Cryolite is used in the extraction of aluminum to increase the melting point of alumina. {F}

Bauxite is the ore of iron. {F}

The process of roasting involves heating an ore in the presence of oxygen. {T}

//Fill in the blanks

The process of heating an ore in the absence of oxygen is called __________.
{
~ Roasting
= Calcination
~ Smelting
}

__________ is added to remove impurities in the form of slag.
{
= Flux
~ Gangue
~ Cryolite
}

The electrolyte used in the extraction of aluminum is a mixture of alumina and __________.
{
~ NaCl
= Cryolite
~ CaCO₃
}

The main ore of aluminum is __________.
{
= Bauxite
~ Galena
~ Magnetite
}

The reduction of metal oxides by carbon is called __________.
{
~ Electrolysis
= Smelting
~ Roasting
}

//Numericals



//Match the following

Match the following items from Column A with their correct corresponding options from Column B\:
{
=Calcination -> Heating in absence of oxygen
=Roasting -> Heating in presence of oxygen
=Gangue -> Impurities in ore
=Cryolite -> Used in extraction of aluminum
=Smelting -> Reduction of metal oxide by carbon
}


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