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Questions Related to chemistry

Statement 1: Lanthanides have much less tendency to form complexes than actinides.
Statement 2: Compared to actinides, the lanthanides have relatively larger size of atoms and less nuclear charge.

chemistry d- and f-block elements comparison of lanthanoids and actinoids actinoids the actinoids

  1. Statement 1 is True, statement 2 is True, statement 2 is a correct explanation of statement 1.

  2. Statement 1 is True, statement 2 is True, statement 2 is not a correct explanation of statement 1.

  3. Statement 1 is true, Statement 2 is False.

  4. Statement 1 is False, Statement 2 is True.

Show answer
Correct Option: A
Explanation:

Because of higher effective nuclear charge and smaller size of atoms the actinides have higher charge density and because of that they have greater tendency to form complexes than the lanthanides.

The main reason for larger number of oxidation states exhibited by the actinoids than the corresponding lanthanoids, is:

chemistry d- and f-block elements comparison of lanthanoids and actinoids actinoids the actinoids

  1. the lesser energy difference between 5f and 6d orbitals than between 4f and 5d orbitals

  2. more energy difference between 5f and 6d orbitals than between 4f and 5d orbitals

  3. greater reactive nature of the actinoids than the lanthanoids

  4. larger atomic size of actinoids than the lanthanoids

Show answer
Correct Option: A
Explanation:

Actinoids shows larger oxidation states due to poor shielding of both $4f$ and $5f$ orbital electrons as a result these orbital have almost similar energy and hence take part in bond formation. Also, there is very small energy between $5f, 6d$ and $7s$ subshells.

The number of oxidation states is exhibited by the actinoids more than by the lanthanide. The main reason for this is:

chemistry d- and f-block elements comparison of lanthanoids and actinoids actinoids the actinoids

  1. more energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals.

  2. the lesser energy difference between 5f and 6d orbitals than between 4f and 5d orbitals.

  3. the greater metallic character of the lanthanoids than that of the corresponding actinoids.

  4. more active nature of the actinoids.

Show answer
Correct Option: B
Explanation:

Actinides show larger oxidation states due to poor shielding of both $4f$ and $5f$ orbital electrons, as a result, their orbitals have almost similar energy and hence take part in bond formation. Thus the energy gap between $5f, 6d$ and $7s$ become very small.

Which of the following statement is incorrect?

aluminium patterns and properties of metals chemistry

  1. $Al$ reacts with excess $NaOH$ to give $Al{(OH)} _{3}$

  2. $NaH{CO} _{3}$ on heating gives ${Na} _{2}{CO} _{3}$

  3. Pure sodium metal dissolves in liquid ammonia to give blue solution

  4. $NaOH$ reacts with glass to give sodium silicate

Show answer
Correct Option: A
Explanation:

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:

aluminium patterns and properties of metals chemistry

  1. $AlH _3$

  2. $(AlH _3) _n$

  3. $LiAlH _4$

  4. none

Show answer
Correct Option: A
Explanation:

Alane is a hydride of aluminium.

It can be represented by the formula $AlH _3$.

Which of the following compounds can make clothes fire proof ?

aluminium patterns and properties of metals chemistry

  1. $FeSO _{4}$

  2. $Al _{2}(SO _{4}) _{3}$

  3. $Cu _{2}SO _{4}$

  4. $MgSO _{4}.7H _{2}O$

Show answer
Correct Option: B
Explanation:

$Al _2(SO _4) _3$ used to make fire proof clothes.

The hydroxide, which is soluble in excess of sodium hydroxide is:

aluminium patterns and properties of metals chemistry

  1. $Fe(OH) _{3}$

  2. $Cu(OH) _{2}$

  3. $Cr(OH) _{3}$

  4. $Al(OH) _{3}$

Show answer
Correct Option: D
Explanation:

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.

$Al(OH) _3 + NaOH \rightarrow Na[Al(OH) _4]$

Cryolite is:

aluminium patterns and properties of metals chemistry

  1. ${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina for decreasing electrical conductivity

  2. ${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina for lowering the melting point of alumina

  3. ${Na} _{3}Al{F} _{6}$ and is used in the electrolytic purification of alumina

  4. ${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina

Show answer
Correct Option: B,D
Explanation:
  • 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:

aluminium patterns and properties of metals chemistry

  1. Bleaching powder is used as a germicide

  2. Chlorine is used in the preparation of

    insecticides like DDT.

  3. Fluorine is used in Rocket fuels

  4. $Na _{3}AlF _{3}$ is not a insecticide

Show answer
Correct Option: D
Explanation:

$Na _{3}AlF _{3}$ is used as a insecticide
So D is false

${ AlO } _{ 2 }^{ - }$ ion in aqueous solution exists as ?

aluminium patterns and properties of metals chemistry

  1. ${ \left[ Al{ \left( OH \right) } _{ 6 } \right] }^{ 2- }$

  2. ${ \left[ Al{ \left( OH \right) } _{ 4 }\left( { H } _{ 2 }O \right) \right] }^{ - }$

  3. ${ \left[ Al{ \left( OH \right) } _{ 4 }{ \left( { H } _{ 2 }O \right) } _{ 2 } \right] }^{ - }$

  4. ${ \left[ Al{ \left( OH \right) } _{ 6 } \right] }^{ - }$

Show answer
Correct Option: C