S - Block MCQ Quiz in मल्याळम - Objective Question with Answer for S - Block - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

CONCEPT:

Ionic Radii and Isoelectronic Species

• Ionic radius refers to the size of an ion in a crystal lattice, and it is influenced by the ion's charge and the number of electrons compared to protons.
• Anions (negatively charged ions) are larger than their parent atoms because they gain electrons, increasing electron-electron repulsion, which pushes the electrons farther from the nucleus.
• Cations (positively charged ions) are smaller than their parent atoms because they lose electrons, which reduces electron-electron repulsion, and the remaining electrons are pulled closer to the nucleus by the protons.
• For isoelectronic species (ions that have the same number of electrons), the size of the ion decreases as the nuclear charge increases (i.e., the number of protons in the nucleus increases).

EXPLANATION:

• The ions N³⁻, O²⁻, F⁻, and Na⁺ all have 10 electrons, making them isoelectronic species. However, they have different nuclear charges (number of protons), which affects the ionic radius.
• The nuclear charge increases as we move from N^3- (7 protons) to Na⁺ (11 protons), meaning that the nucleus can pull the electrons closer to itself more effectively in species with higher nuclear charge.
• This leads to the following trend in ionic radii:
  • N^3- has the smallest nuclear charge (7 protons) and thus the largest ionic radius because the attraction between the nucleus and the electrons is weakest.
  • O^2- has 8 protons, so it has a smaller ionic radius than N^3- because the nucleus pulls the electrons more tightly.
  • F⁻ has 9 protons, so it has a smaller ionic radius than O^2-.
  • Na⁺ has the highest nuclear charge (11 protons), making it the smallest ion because the nucleus pulls the electrons most tightly. 

Additional Information

• Trend Among Isoelectronic Species: The size of isoelectronic ions decreases as the positive charge on the nucleus increases. Therefore, for isoelectronic species, cations are smaller than anions.
• Factors Influencing Ionic Radius:
  • As the number of protons increases, the effective nuclear charge increases, pulling the electron cloud closer and reducing the size of the ion.
  • For anions, adding electrons increases repulsion between electrons, causing the ionic radius to expand.

Conclusion:

The correct answer is Option 1: N^3- > O^2- > F^- > Na⁺

EXPLANATION 

Fajan's Rule:

• Fajan's Rule helps in predicting the covalent character in ionic compounds.
• According to this rule, smaller cations and larger anions tend to increase the covalent character of a compound.
• Cations with a higher charge and anions with a lower charge to size ratio tend to have more covalent character.

 

According to Fajan's rule, the ionic compound which is formed by small cation and large anion has more covalent character than other ionic comp. according to Fajan's rule 

A. KF > KI – False LiF > KF – True

B. KF < KI – True LiF > KF – True

C. SnCl4 > SnCl2 – True C4Cl > NaCl –True

D. LiF > KF – True C4Cl > NaCl – False

E. KF < KI – True C4Cl > NaCl – True

Since Options B, C, and E match the correct statements, we conclude:

The correct answer is Option 2: B, C, E only.

Concept -

Oxides - 

The basic nature of oxides increases down the group and decreases along a period

Oxides are the compound of oxygen with other elements in which the oxidation state of 'O' is -2.

• Oxide is generally an anion of oxygen with oxidation number -2 or simply it is O2-.
• For example; NO, MgO, Na2O, etc.

Oxides are classified into four categories based on their acid-base characteristics. These are - 

1. Acidic oxides 
2. Basic oxides 
3. Amphoteric oxides 
4. Neutral oxides 

Nature of oxides -

Generally,

• Metals form basic oxides because they can donate electrons and non-metals form acidic oxides because they can accept electrons.
• The basic nature of oxides increases down the group and decreases along a period, for ex - MgO, CaO, etc.
• Amphoteric oxides are those which behave as both acidic and basic oxides. They can react with acid as well as the base.  For example - BeO, Al2O3, etc.
• Neutral oxides are neither acidic nor basic. For example - H2O, N2O, CO, etc

Explanation:

→The basic nature of oxides increases down the group and decreases along a period.

→Metals form basic oxides because they can donate electrons and non-metals form acidic oxides because they can accept electrons.

Among the given elements,

• potassium is having most metallic in nature, hence form most basic oxide.
• Na lie before K in group 1, therefore, the oxide of Na is less basic than oxide of K or Na₂O < K₂O.
• In a period, basic nature of oxides decreases therefore, MgO <  Na2O < K2O.
• Oxide of Aluminum is amphoteric in nature as it can react with acid as well as the base and hence 

Al2O3 < MgO < Na2O < K2O.

Conclusion:

Therefore, the set representing the correct increasing order of basic character is, Al2O3 < MgO < Na2O < K2O

The correct answer is Alkali metal group.

Key Points

• Alkali Metals:
  • Group 1 of the periodic table consists of namely, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). 
• Properties of Alkali metals:
  • They have high thermal and electrical conductivity, lustre, ductility, and malleability.
  • All these elements react with water to form hydrogen gas.
  • Each of these, alkali metal atoms has a single electron in its outermost shell. Hence, their valency is 1.

Concept:

• Non metals exist in solid liquid and gases state.
• They are all placed in p-block towards right hand side of periodic table from group no 13 to 18.

Explanation:

• Talking about halogen they are placed in group 17
• Member of this family include Fluorine(F) Chlorine (Cl), Bromine(Br), Iodine(I), Astatine(At), and Tennessine(Ts).
• Among these only Br exist in liquid state and F, Cl, exist in gases state while Iodine is a solid.
• As the atomic no. increases the Vander waal force of attraction increases. 
• In case of Br intermolecular forces are strong enough so that it does not evaporate.
• Bromine forms diatomic molecules and Van der Waals interactions are sufficiently strong.
• Also Br is more reactive than Iodine but less reactive than Cl.
• After Br, as we move down the group iodine occur as solid because Vander Waal forces become more stronger than Br and hence physical state become dense.
• We conclude that down the group the physical state become more denser therefore we observed that F, Cl are gases, Br is liquid and I is solid.
• Among other non-metals like Carbon, Sulphur, Phosphorous, etc are solid whereas Oxygen, Nitrogen, are gases.

​

Correct answer: 1)

Concept:

• Carbonates of alkaline earth metals are insoluble in water and can be precipitated by the addition of a sodium or ammonium carbonate solution to a solution of a soluble salt of these metals.
• Solubility of carbonates decreases down the group.
• All the carbonates decompose on heating to give carbon dioxide and oxide.
• Beryllium carbonate is unstable and can be kept only in the atmosphere of CO2.
• The thermal stability of carbonates increases down the group.

Explanation:

• Beryllium carbonate is unstable due to the smaller size of the cation and larger size of the anion (as smaller cation stabilizes smaller anion through crystal lattice energy) and can be kept only in the atmosphere of CO2​.
• The thermal stability increases with increasing cationic size.
• BeCO3
• BeCO3 →BeO+CO2
• Since the decomposition reaction is reversible, therefore, to increase the stability of BeCO3 or to reverse the above equilibrium.
• Thus, kept only in the atmosphere of CO2.
• BeCO3" id="MathJax-Element-2-Frame" role="presentation" style=" position: relative;" tabindex="0">" id="MathJax-Element-32-Frame" role="presentation" style="position: relative;" tabindex="0">  is unstable due to strong polarizing the effect of small Be2+ ion on the large polarisable carbonation.
• Moreover, extra stability of the oxide is achieved through lattice energy by packing small cations with small oxide ions.
• Beryllium carbonate is unstable and can be kept only in the atmosphere of CO2.

Conclusion:

Thus, Beryllium carbonate is unstable and can be kept only in the atmosphere of CO2.

Correct answer: 3) 

Concept:

• Lime water is a hydroxide of calcium (an alkaline earth metal).
• Thus, lime water is calcium hydroxide.
• The chemical formula of calcium hydroxide is Ca(OH)₂.
• It is sparingly soluble in water. The suspension of slaked lime in water is known as milk of lime.
• Milk of lime reacts with chlorine to form hypochlorite, a constituent of bleaching powder.
• It is used in the tanning industry, for the preparation of bleaching powder and for the purification of sugar.

Explanation:

• Calcium hydroxide is prepared by adding water to quicklime(CaO)" id="MathJax-Element-1-Frame" role="presentation" tabindex="0">(CaO).
• CaO(s)+H₂O(l)→Ca(OH)₂(s)
• It is a white amorphous powder.
• It is sparingly soluble in water.
• It forms a suspension of slaked lime in water which is called milk of lime and the clear solution obtained after the suspension settles is known as lime water.
• The aqueous solution is known as lime water and a suspension of slaked lime in water is known as milk of lime.
• Calcium hydroxide dissociates in an aqueous solution, releasing calcium cations and hydroxide anions.
• Calcium oxide is the chemical compound known as quicklime. Milk of lime is a term used to describe the suspension of slaked lime in water.

 

Conclusion:

 

Thus, the suspension of slaked lime in water is known as milk of lime.

Additional Information

Concept:

According to Fajan’s rule, greater the polarizing power of cation greater would be the covalent character.

Fajans' rules is used to predict whether a chemical bond will be covalent or ionic and depend on the charge on the cation and the relative sizes of the cation and anion. All of the alkaline earth metal is reacting with the halogens to form the alkaline earth metal halides.

SinceBe²⁺, has maximum polarizing power among the given cations. Therefore, BeX₂ would be most covalent alkaline earth metal halides among the given halides.

Properties of Halides of Alkali Earth Metals:

All beryllium halides are essentially covalent and are soluble in organic solvents. The halides of all other alkaline earth metals are ionic. Except BeCl₂ all other chlorides of group 2 form hydrates but their tendency to form hydrates decrease.

Concept:

Smaller in size of center atoms more water molecules will crystallize hence Ba(NO₃)₂ is answer due to its largest size of '+ve' ion.

\({\rm{Ba}}{\left( {{\rm{N}}{{\rm{O}}_3}} \right)_2} \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\leftharpoonup\over {\smash{\rightharpoondown}}$}} B{a^{2 + }} + 2NO_3^ - \)

Action of alkali metals with water compounds contain acidic hydrogen reacts readily forming hydroxides with the liberation of hydrogen.

Some of the physical properties of the compound earth metals are:

• They are silverfish, white, and hard metals. They are soft but harder than alkali metals in comparison.
• Some of them appear whitish by beryllium and magnesium appear greyish in colour.
• Their melting and boiling points are higher compared to the alkali metals.
• These metals are strongly electropositive in nature. Alkaline earth metals give a different colour with the flame test such as calcium gives brick red colour, strontium gives crimson colour and barium gives apple green colour, all of which are different for different metals.

Some of chemical properties of the compound earth metals are:

• All alkaline earth metals tend to form monoxide except the metal, beryllium.
• They usually have high electrical and thermal conductivities as they have a metallic bonding.
• The oxides of alkaline earth metal are basic but less basic in comparison to alkali metals.
• Alkali earth metal form solid carbonates. As one move from beryllium to barium thermal stability of carbonated usually increases.

CONCEPT:

Diagonal Relationship in the Periodic Table

• The diagonal relationship in the periodic table refers to the similarity in properties between certain pairs of diagonally adjacent elements in the periodic table.
• This relationship is observed due to similarities in ionic sizes, charge/radius ratio, and electronegativities of these elements.
• In the case of lithium, it shows a diagonal relationship with magnesium.

EXPLANATION:

• Lithium (Li) is the first element in Group 1 (alkali metals), while magnesium (Mg) is the second element in Group 2 (alkaline earth metals).
• The diagonal relationship arises because:
  • The atomic radius of lithium (Li) is similar to that of magnesium (Mg).
  • The charge/radius ratio of Li⁺ (ion of lithium) is similar to that of Mg²⁺ (ion of magnesium).
  • The electronegativities and ionization energies of lithium and magnesium are also comparable, leading to similar chemical behavior.
• Examples of similar properties between lithium and magnesium:
  • Both lithium and magnesium form nitrides directly when they react with nitrogen (e.g., Li₃N and Mg₃N₂).
  • Both form covalent organometallic compounds (e.g., organolithium and Grignard reagents).
  • Both their chlorides (LiCl and MgCl₂) are deliquescent and soluble in organic solvents like ethanol.

Therefore, lithium shows a diagonal relationship with magnesium.