Tag: the s-block elements (alkali and alkaline earth metals)

Questions Related to the s-block elements (alkali and alkaline earth metals)

Which of the following illustrate the anomalous properties of Lithium?

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. Lithium is softer than the other group I metals

  2. Lithium forms nitride, $Li _3N$ unlike other group I metals

  3. The melting and boiling point of Lithium are comparatively high

  4. none of these

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Correct Option: B,C
Explanation:

Similarities of  lithium with magnesium and dissimilarities with that of the other members of the group

Lithium is a very strong element and is equally strong as magnesium.

Li forms $Li _3N$ with nitrogen.

It has high melting and boiling points. The boiling point of lithium is $1330$ degree centigrade that is comparable to that of magnesium which is $1100$ degrees.

Due to small size, the lithium atom has high ionization energy. Hence, it remains inactive to dry air, slowly reactivity with water, liquid bromine and forms a highly stable hydride unlike other alkali metals.

Lithium react less vigorously with water than other metals. Give reason behind it.

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. Lithium has most negative $E^\ominus $ value

  2. Lithium has small size and very high hydration energy.

  3. Lithium has least negative $E^\ominus $ value

  4. Both (a) and (b)

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Correct Option: A,B

$LiAlH 4$ is obtained by reacting an excess of ____  with an ethereal solution of $AlCl _3$:

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. $LiCl$

  2. $LiH$

  3. $Li$

  4. $LiOH$

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Correct Option: B
Explanation:

The reaction is ,


$4LiH + AlCl _3 \rightarrow LiAlH _4 + 3 LiCl$


by reacting $LiH$ in the presence of dry ether with $AlCl _3$ .

There is loss in weight when mixture of $Li _{2}CO _{3}$ and $Na _{2}CO _{3}\cdot10H _{2}O$ is heate strongly. This loss is due to :

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. $Li _{2}CO _{3}$

  2. $Na _{2}CO _{3}\cdot10H _{2}O$

  3. both (a) and (b)

  4. none of these

Show answer
Correct Option: C
Explanation:

Loss in weight due to following reactions:
$Li _{2}CO _{3} \rightarrow Li _{2}O+CO _{2} \uparrow$
$Na _{2}CO _{3}\cdot10H _{2}O \rightarrow Na _{2}CO _{3} + 10H _{2}O \uparrow$
As sodium carbonate is thermally stable so it will not dissociates on heating.

Nitrate can be converted into metal oxide on heating in case of :

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. Li

  2. Na

  3. both (a) and (b)

  4. None of these

Show answer
Correct Option: A
Explanation:

Reaction on heating:
$2LiNO _{3} \rightarrow Li _{2}O+2NO _{2}+ \frac{1}{2} O _{2}$
$Mg(NO _{3}) _{2} \rightarrow MgO+2NO _{2}+ \frac{1}{2} O _{2}$
$2NaNO _3\rightarrow 2NaNO _2+O _2$

Lithium selenide can be described as a cubic closest-packed array of selenide ions with lithium ions in all of the tetrahedral holes. Formula of lithium selenide is 

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. $L{i _2}Se$

  2. $LiSe$

  3. $LiS{e _2}$

  4. $L{i _3}Se$

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Correct Option: A
Explanation:

Answer(A):- $Li _2Se$

If number of Se =Z , Number of Li = 2Z

Which one of the following species dose not exist under normal conditions?

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. $Li _2$

  2. ${ Be } _{ 2 }^{ + }$

  3. $Be _2$

  4. $B _2$

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Correct Option: A

Which of the following carbonate is not stable to heat.

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. $Li _2CO _3$

  2. $Na _2CO _3$

  3. $K _2CO _3$

  4. $Rb _2CO _3$

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Correct Option: A

Which one of the alkali metals,forms only,the normal oxide $M _2O$ on heating in air?

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. $Li$

  2. $Na$

  3. $Rb$

  4. $K$

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Correct Option: A

Li has chemical properties most similar to :

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. Al

  2. Ca

  3. Mg

  4. Ti

Show answer
Correct Option: C
Explanation:

Li has chemical properties most similar to Mg due to diagonal relationship.
Both exhibits same properties like
(i).

$MgCO _3\, \overset{\Delta}{\rightarrow}\, MgO\, +\, CO _2$
$Li _2CO _3\, \overset{\Delta}{\rightarrow}\, Li _2O\, +\, CO _2$

(ii).
$3Mg\, +\, N _2\, \rightarrow Mg _3N _2$ 
$6Li+ N _2 \rightarrow 2Li _3N$

Hence option C is correct answer.