Chemistry · Science General

Periodic Table and Elements

406 Questions

The periodic table and elements questions test knowledge of chemical properties, atomic structures, and periodic trends. Topics include alkali metals, transition elements, and ionisation potential. These concepts frequently appear in general science sections of competitive examinations.

Alkali metals propertiesTransition elementsLattice energyIonisation potentialAlkaline earth metals

Periodic Table and Elements Questions

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

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 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

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.

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 illustrate the anomalous properties of Lithium?

  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
Reveal answer Fill a bubble to check yourself
B,C Correct answer
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.

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 species dose not exist under normal conditions?

  1. $Li _2$
  2. ${ Be } _{ 2 }^{ + }$
  3. $Be _2$
  4. $B _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Li2 (dilithium) does not exist under normal conditions due to poor orbital overlap and bond formation. Be2+ exists as the beryllium(II) ion, Be2 as a molecule is unstable but Be2+ is common. B2 exists as a diatomic molecule (paramagnetic with 2 unpaired electrons). The question asks which doesn't exist - Li2 is the correct answer.

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

  1. $Li$
  2. $Na$
  3. $Rb$
  4. $K$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lithium forms only the normal oxide Li2O on heating in air. Sodium forms Na2O2 (peroxide), and potassium/rubidium form superoxides (KO2, RbO2) under similar conditions. This is due to the small size of Li+ ion.

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

Li has chemical properties most similar to :

  1. Al

  2. Ca

  3. Mg

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

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

Li resembles to element X which is not the member of alkali metals. The group of X is?

  1. II

  2. III

  3. IV

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

Li resembles to element X which is not a member of alkali metals. The group of X must be II group, because certain elements of 2nd period show similarity with their diagonal elements in the 3rd period as shown below : Thus, Li resembles Mg, Be resembles Al and B resembles Si. This is called diagonal relationship and is due to the reason that these pairs of element have almost identical ionic radii and polarizing power (i.e. charge/size ratio). Element of second period are known as bridge elements.

So Li is I st group element and the diagonal element Mg is II nd group element.
Hence option A is correct.

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

$Mg$ and $Li$ and similar in their properties due to:

  1. same $\dfrac {e}{m}$ ratio

  2. same electron affinity

  3. same group

  4. same radius
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Li$ and $Mg$ show diagonal relationship due to the similarity in size (radius), electronegativity, ionisation enthalpy and charge/radius ratio.

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

Li resembles to element X which is not the member of alkali metals.
The element X is :

  1. Mg

  2. Be

  3. Ca

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

Li resembles to element X which is not the member of alkali metals. The element X is Mg. This is due to diagonal relationship. Certain elements of 2nd period show similarity with their diagonal elements in the 3rd period as shown below : Thus, Li resembles Mg, Be resembles Al and B resembles Si. 


This is called diagonal relationship and is due to the reason that these pairs of element have almost identical ionic radii and polarizing power (i.e. charge/size ratio). Element of second period are known as bridge elements.   
Hence option A is correct.

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 shows similarities with magnesium in its chemical behaviour because :

  1. similar size, greater electronegativity and lower polarising power

  2. similar size, same electronegativity, and lower polarising power

  3. similar size, same electronegativity and similar high polarising power

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lithium shows similarities with magnesium in its chemical behaviour because they have similar size and charge/size ratio. They have similar electronegativity.


This type of diagonal similarity is commonly referred to as diagonal relationship in the periodic table.

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

In certain matters, lithium differs from other alkali metals; the main reason for this is :  

  1. small size of lithium atom and $Li^+$.
  2. extremely high electropositivity of $Li$.
  3. greater hardness of $Li$.
  4. hydration of $Li^+$ ion.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In certain matters, lithium differs from other alkali metals(anamalous property); the main reason for this is small size of lithium atom and $Li^+$ and high polarizing power.

Hence option A is correct.