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

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

The close resemblance between the properties of an element of 2nd period with those of the element of 3rd period belonging to the next group is called:

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. periodicity

  2. periodic trend

  3. diagonal relationship

  4. group trend

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Correct Option: C
Explanation:

Option $(C)$ is correct.

The close resemblance between the properties of an element of 2nd period with those of the element of 3rd period belonging to the next group is called diagonal relationship.
These pairs (lithium and magnesium, beryllium and aluminium, boron and silicon etc.) exhibit similar properties.

What is the main reason of diagonal relationship between lithium and magnesium?

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. Electronegativity remains constant the same on moving parallel.

  2. Electronegativity remains constant the same on moving horizontally.

  3. Electronegativity remains constant the same on moving diagonally.

  4. Electronegativity remains constant the same on moving vertically.

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Correct Option: C
Explanation:

The diagonally opposite elements possess almost similar electronegativities and there fore almost similar electropositive character.

Lithium salts are mostly hydrated like $ LiCl.2H _2O $ 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. maximum ionisation enthalpy

  2. maximum degree of hydration of $Li^+$

  3. maximum hydroscopic nature

  4. maximum chemical reactivity.

Show answer
Correct Option: B
Explanation:

$ { Li }^{ + } $ ion being small in size is surrounded by large no. of water molecules on account of which it has very hydration energy. Hence, it is heavily hydrated and have high degree of hydration.

Which one of the following pairs of elements does not have diagonal relationship?

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. $Li$ and $Mg$

  2. $Be$ and $Al$

  3. $B$ and $Si$

  4. $Be$ and $Na$

Show answer
Correct Option: D
Explanation:

Option $(D)$ is correct.

$Be$ and $Na$ does not have diagonal relationship.
A diagonal relationship is said to exist between certain pairs of diagonally adjacent elements in the second and third periods of the periodic table. These pairs (lithium and magnesium, beryllium and aluminium, boron and silicon etc.) exhibit similar properties.

Li shows diagonal relationship with:

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. Mg

  2. Be

  3. Al

  4. B

Show answer
Correct Option: A
Explanation:

This is because of almost same size and electronegativity values of magnesium and lithium, the show similar properties.

Which of the following statement is not correct.

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. LiOH is amphoteric in nature.

  2. LiCl is soluble in pyridine.

  3. $Li _3N$ is stable while $Na _3N$ doesn't exist even at room temperature.

  4. BeO is amphoteric in nature.

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Correct Option: A

Which of the following metals can form nitride with nitrogen ?

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. $Mg$

  4. $Ca$

Show answer
Correct Option: A
Explanation:

Lithium is the only alkali metal which combines directly with nitrigen to form lithium nitride.


$Li _{(s)}+N _{2(g)}\longrightarrow 2Li _3N _{(s)}$


As lithium is the smallest alkali metal, $Li^+$ will have the highest positive charge density.

As nitride $(N^{3-})$ ion is an extremely small highly charged anion, it forms stable ionic compound with cations of high positive charge density, i.e. $Li^{+}$.

The products obtained on heating $LiNO _3$ will be?

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. $LiNO _2+O _2$

  2. $Li _2O+NO _2+O _2$

  3. $Li _3N+O _2$

  4. $Li _2O+NO+O _2$

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Correct Option: B

Which elements does not combine directly with nitrogen at high temperature?

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. Rb

  3. Sr

  4. Mg

Show answer
Correct Option: B
Explanation:

Only $Rb$ does not combine with $N _2$ at high temperature. Because heavier metals like $Rb$ are seen to be chemically inactive towards $N _2$ upon heating.


Since the nitride ion holds a high formal charge $(N^{3-})$ and contains an adverse molar ration of cations to anions $(3:1)$ 

it is impossible to form a stable structure. But alkali metal $Li$ can react with $N _2$ at room temperature. $Sr$ and $Mg$ can react with $N _2$ at high temperature.

So, the correct option is $Rb$

Which of the following on heating gives oxides quickly ?

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. ${ Na } _{ 2 }{ CO } _{ 3 }$

  2. ${ K } _{ 2 }{ CO } _{ 3 }$

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

  4. ${ Rb } _{ 2 }{ CO } _{ 3 }$

Show answer
Correct Option: C
Explanation:

$N{a _2}C{O _3} \to state\,\,than\,\,L{i _2}C{O _3}$

${K _2}C{O _3}$ and $R{b _2}C{O _3}$
Stablitiy of carbaonate $ \uparrow $ down the gap or size $ \uparrow    CO _3^{2 - } $ more stable.
$L{i _2}C{o _3} \to L{i _2}O + C{o _2}$.
Hence, option $C$ is correct answer.