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Questions Related to chemistry

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.

Show answer
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. $Li _2O+NO+O _2$

Show answer
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.

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

Show answer
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)

Show answer
Correct Option: A,B