Tag: aluminium
Questions Related to aluminium
Which of the following statement is incorrect?
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$Al$ reacts with excess $NaOH$ to give $Al{(OH)} _{3}$
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$NaH{CO} _{3}$ on heating gives ${Na} _{2}{CO} _{3}$
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Pure sodium metal dissolves in liquid ammonia to give blue solution
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$NaOH$ reacts with glass to give sodium silicate
Sodium aluminate is also formed by the action of sodium hydroxide
on elemental aluminium which is an amphoteric metal. The reaction is
highly exothermic once established and is accompanied by the rapid
evolution of hydrogen gas. The reaction is written as:
$2Al+2NaOH+{ 2H } _{ 2 }O\longrightarrow 2NaAlO _{ 2 }+3{ H }$
$2NaHCO _{ 3 (S) }\longrightarrow N{ a } _{ 2 }CO _{ 3 (S) }+CO _{ 2 (g) }+{ H } _{ 2 }O _{ (l) }$ This statment is correct.
By the reaction of sodium with liquid ammonia sodium ammide can be prepared.Sodium (alkali metal)dissolves in liquid ammoia solution to form a blue solution characteristic of a solvated electron in liquid ammonia, which is conducting in nature, due to ammoniated electrons (solvated electron).
This statment is correct.
Sodium silicate liquid can also be prepared directly by dissolving
silica sand under pressure in a heated aqueous solution of caustic soda
(sodium hydroxide, NaOH):
$2NaOH+{ SiO } _{ 2 }\longrightarrow Na _{ 2 }O.{ SiO } _{ 2 }+{ H } _{ 2 }O$
This statment is correct.
Alane is chemically:
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$AlH _3$
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$(AlH _3) _n$
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$LiAlH _4$
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none
Alane is a hydride of aluminium.
Which of the following compounds can make clothes fire proof ?
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$FeSO _{4}$
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$Al _{2}(SO _{4}) _{3}$
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$Cu _{2}SO _{4}$
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$MgSO _{4}.7H _{2}O$
$Al _2(SO _4) _3$ used to make fire proof clothes.
The hydroxide, which is soluble in excess of sodium hydroxide is:
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$Fe(OH) _{3}$
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$Cu(OH) _{2}$
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$Cr(OH) _{3}$
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$Al(OH) _{3}$
Aluminium hydroxide is insoluble in $H _2O$ but it is soluble in strong acids and strong bases. This is because of $Al(OH) _3$ its amphoteric nature.
Cryolite is:
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${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina for decreasing electrical conductivity
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${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina for lowering the melting point of alumina
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${Na} _{3}Al{F} _{6}$ and is used in the electrolytic purification of alumina
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${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina
- Molten cryolite $(Na _3AlF _6)$ is used as a solvent for aluminium oxide $(Al _2O _3)$ in the Hall–Héroult process, used in the refining of aluminium.
- It decreases the melting point of molten (liquid state) aluminium oxide to 900-1000 °C from 2000-2500 °C. Thus cryolite makes the extraction of aluminium profitable.
- Hence both option B and D are correct .
The incorrect statement among the following is:
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Bleaching powder is used as a germicide
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Chlorine is used in the preparation of
insecticides like DDT. -
Fluorine is used in Rocket fuels
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$Na _{3}AlF _{3}$ is not a insecticide
$Na _{3}AlF _{3}$ is used as a insecticide
So D is false
${ AlO } _{ 2 }^{ - }$ ion in aqueous solution exists as ?
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${ \left[ Al{ \left( OH \right) } _{ 6 } \right] }^{ 2- }$
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${ \left[ Al{ \left( OH \right) } _{ 4 }\left( { H } _{ 2 }O \right) \right] }^{ - }$
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${ \left[ Al{ \left( OH \right) } _{ 4 }{ \left( { H } _{ 2 }O \right) } _{ 2 } \right] }^{ - }$
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${ \left[ Al{ \left( OH \right) } _{ 6 } \right] }^{ - }$
Which of the statement about aluminium is not correct?
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It liberates hydrogen from acid as well as alkalies
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It liberates hydrogen from acid but not from alkalies
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It liberates hydrogen from hot alkali solution
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It liberates hydrogen from boiling water
Solution:- (B) It liberates hydrogen from acid but not from alkalies
The common impurities present in bauxite are:
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${ Fe } _{ 2 }{ O } _{ 3 },{ SiO } _{ 2 }$
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$NaCl,{ MgCl } _{ 2 }$
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${ AlCl } _{ 3 },{ MgCl } _{ 2 }$
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${ CaCl } _{ 2 },{ MgCl } _{ 2 }$
Bauxite has a number of impurities in it including iron oxides(hematite and goethite), $Fe _2O _3$ the sand silicon dioxide $SiO _2$ the clay mineral Kaolinite and asmall amount of $TiO _2$ known as Anatase.
In the purification of $Al$ by Hoop's process the correct statement is
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electrolytic cell is iron and it contains three layer mass
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upper layer is pure $Al$ and Carbon rods in it are cathode and the bottom layer contains impure $Al$ and carbon lining of the cell is anode
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Electrolyte is the middle layer with fused mixture of flouride.
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All of the above