Tag: group 1 elements: alkali metals

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

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:

  1. periodicity

  2. periodic trend

  3. diagonal relationship

  4. group trend
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  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.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

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

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

Lithium salts are mostly hydrated like $ LiCl.2H _2O $ due to:

  1. maximum ionisation enthalpy
  2. maximum degree of hydration of $Li^+$

  3. maximum hydroscopic nature

  4. maximum chemical reactivity.
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. $Li$ and $Mg$
  2. $Be$ and $Al$
  3. $B$ and $Si$
  4. $Be$ and $Na$
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

Which of the following statement is not correct.

  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.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Statement A is incorrect because LiOH is basic, not amphoteric. BeO is amphoteric (statement D is correct). LiCl is indeed soluble in pyridine (statement B is correct). Li3N is stable while Na3N doesn't exist (statement C is correct). The question asks for the INCORRECT statement, which is A.

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

Which of the following metals can form nitride with nitrogen ?

  1. $Li$
  2. $Na$
  3. $Mg$
  4. $Ca$
Reveal answer Fill a bubble to check yourself
A Correct answer
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. $Li^{+}$.

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

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

  1. $LiNO _2+O _2$
  2. $Li _2O+NO _2+O _2$
  3. $Li _3N+O _2$
  4. $Li _2O+NO+O _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When LiNO3 is heated, it decomposes to Li2O, NO2, and O2. This is typical thermal decomposition of lithium nitrate. Option A gives nitrite, option C suggests nitride formation, and option D gives NO instead of NO2.

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

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

  1. Li

  2. Rb

  3. Sr

  4. Mg
Reveal answer Fill a bubble to check yourself
B Correct answer
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 $Rb$

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

Which of the following on heating gives oxides quickly ?

  1. ${ Na } _{ 2 }{ CO } _{ 3 }$
  2. ${ K } _{ 2 }{ CO } _{ 3 }$
  3. ${ Li } _{ 2 }{ CO } _{ 3 }$
  4. ${ Rb } _{ 2 }{ CO } _{ 3 }$
Reveal answer Fill a bubble to check yourself
C Correct answer
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.