Group 16 Elements (Oxygen Family) MCQ Quiz - Objective Question with Answer for Group 16 Elements (Oxygen Family) - Download Free PDF

CONCEPT:

Basicity of Oxides

• The basicity of oxides depends on the electronegativity of the element and the nature of the oxide.
• Oxides of metals generally tend to be basic, whereas oxides of non-metals tend to be acidic.
• The basic nature of an oxide increases as we move down a group in the periodic table, because the metallic character increases.
• The basicity of an oxide also increases as the oxidation state of the metal decreases. Lower oxidation states tend to form more basic oxides.

EXPLANATION:

•  
  • Sb₂O₃ (Antimony(III) oxide): Antimony is a post-transition metal, and the oxide is moderately basic.
  • Bi₂O₃ (Bismuth(III) oxide): Bismuth is a heavier post-transition metal, and its oxide is also basic but less so compared to Sb₂O₃.
  • SeO₂ (Selenium dioxide): Selenium is a non-metal, and its oxide is acidic in nature.
  • Al₂O₃ (Aluminum oxide): Aluminum is a metal, and its oxide is amphoteric, meaning it can act both as an acid and as a base depending on the conditions.
• Among the given oxides, Bi₂O₃ is most basic, as it is from a metal with a lower oxidation state and is less acidic or amphoteric compared to the others.

Therefore, Bi₂O₃ is the most basic oxide among the given options.

Concept:

Formation of Sodium Thiosulphate (Na₂S₂O₃)

• Sodium thiosulphate is synthesized through various chemical reactions involving sulfite compounds and sulfur.
• One common method involves the reaction of sodium sulfite (Na₂SO₃) with elemental sulfur.

Explanation:

• When a solution of sodium sulfite (Na₂SO₃) is heated with finely powdered sulfur, sodium thiosulphate (Na₂S₂O₃) is formed.
  • Reaction: Na₂SO₃ ​+ S → Na₂​S₂​O₃​
• Treating NaHSO₃ with NaHS does not form sodium thiosulphate.
• Adding iodine (I₂) to a mixture of Na₂S and Na₂SO₃ does not form sodium thiosulphate. It might reduce iodine but does not necessarily form Na₂S₂O₃.
• Incorrect since Option 1 is a valid method for forming sodium thiosulphate.

Conclusion:

The correct statement is:  A solution of Na2SO3 is heated with finely powdered sulfur.

Concept:

Paramagnetic substances have unpaired electrons, which align with an external magnetic field, making them attracted to the field. In the vapour state, sulphur forms diatomic S₂ molecules, which resemble O₂ and exhibit paramagnetism due to unpaired electrons in π* orbitals.

Explanation:

• Assertion (A): This is correct because sulphur in the vapour state exhibits paramagnetism.

• Reason (R): This is also correct because S₂ molecules in the vapour state have two unpaired electrons in antibonding π* orbitals, similar to O₂, leading to paramagnetism.

  • 

Conclusion:

The correct answer is: Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).

Concept:
Oxyacids of sulfur are compounds where sulfur is bonded to oxygen and hydrogen, and they differ in the oxidation state of sulfur based on the number of oxygen atoms attached.

Explanation:

• Peroxodisulfuric acid: In H₂S₂O₈, sulfur is in the +6 oxidation state.

• Thiosulfuric acid: In H₂S₂O₃, one sulfur is in the +4 oxidation state, and the other is in the -2 state. However, the average oxidation state of sulfur in this compound is +2.

• Dithionic acid: In H₂S₂O₆, sulfur is in the +5 oxidation state.

• Sulfurous acid: In H₂SO₃, sulfur is in the +4 oxidation state.

• Polythionic acid: In H₂S_nO₆, the average oxidation state depends on the number of sulfur atoms, but it can vary between +1 and +2.

• Sulfuric acid: In H₂SO₄, sulfur is in the +6 oxidation state.

Conclusion:
The correct matching is (A) - (vi), (B) - (v), (C) - (iii), (D) - (ii), (E) - (v), (F) - (i)

Concept:

Oxoacids are basically the acids that contain oxygen. Sulphur is known to form many oxoacids. In oxoacids of sulphur, Sulphur exhibits a tetrahedral structure when coordinated to oxygen. Generally, oxoacids of sulphur contain at least one S=O bond and one S-OH bond. Terminal peroxide groups, terminal S=S, terminal and bridging oxygen atoms and chains of (-S-)_n are also observed in addition to S=S and S-OH.

H₂S₂O₃ is called as Thiosulfuric acid. The oxidation number is −2 (for the terminal sulphur), +6 (for the central atom). Since sulphur contains bond between sulphur atoms.

H₂S₂O₄ is called as Dithionous acid. The oxidation number is +3 and the structure has two sulphur bonding between each other.

H₂S₄O₆ is called as polythionic acid. The oxidation number is 0 (for the bridging S atoms), +5 (for the terminal central S atoms). It also contains sulphur bond between them.

H₂S₂O₇ does not show bonding between sulphur atoms.

Pyrosulphuric acid (H₂S₂O₇) is also known as oleum. It is an anhydride of sulphuric acid, it is a colourless, crystalline solid and has a melting point of 36°C. It can be prepared by reacting excess sulphur trioxide with sulphuric acid. The reaction goes like this:

H₂SO₄ + SO₃ → H₂S₂O₇

It reacts with bases to form salts which are called pyrosulphates.

Pyro sulphuric acid (H₂S₂O₇) is a strong acid which is a main constituent of fuming sulfuric acid (oleum). It is also commonly known as disulphuric acid.

Concept:

Oxoacids are basically the acids that contain oxygen. Sulphur is known to form many oxoacids. In oxoacids of sulphur, Sulphur exhibits a tetrahedral structure when coordinated to oxygen. Generally, oxoacids of sulphur contain at least one S=O bond and one S-OH bond. Terminal peroxide groups, terminal S=S, terminal and bridging oxygen atoms and chains of (-S-)_n are also observed in addition to S=S and S-OH.

H₂S₂O₃ is called as Thiosulfuric acid. The oxidation number is −2 (for the terminal sulphur), +6 (for the central atom). Since sulphur contains bond between sulphur atoms.

H₂S₂O₄ is called as Dithionous acid. The oxidation number is +3 and the structure has two sulphur bonding between each other.

H₂S₄O₆ is called as polythionic acid. The oxidation number is 0 (for the bridging S atoms), +5 (for the terminal central S atoms). It also contains sulphur bond between them.

H₂S₂O₇ does not show bonding between sulphur atoms.

Pyrosulphuric acid (H₂S₂O₇) is also known as oleum. It is an anhydride of sulphuric acid, it is a colourless, crystalline solid and has a melting point of 36°C. It can be prepared by reacting excess sulphur trioxide with sulphuric acid. The reaction goes like this:

H₂SO₄ + SO₃ → H₂S₂O₇

It reacts with bases to form salts which are called pyrosulphates.

Pyro sulphuric acid (H₂S₂O₇) is a strong acid which is a main constituent of fuming sulfuric acid (oleum). It is also commonly known as disulphuric acid.

Thermal stability of group-16 hydrides decreases from H₂O to H₂Po due to decrease in bond dissociation energy.

The thermal stability of hydrides decreases as we move down within a group in the periodic table. This is primarily due to the increasing size of the central atom, which weakens the bond strength between the atom and hydrogen as you move from top to bottom in a group. For group 16 (the chalcogens), water (H₂O) is an anomaly due to its unique hydrogen-bonding capabilities, making it significantly more thermally stable than other hydrides in the same group. Thus, for the given hydrides, the order from least to most thermally stable, considering periodic trends and anomalous behavior of water, would be:

So, correct order of thermal stability is H₂O > H₂S > H₂Se > H₂Te > H₂Po 

CONCEPT:

Basicity of Oxides

• The basicity of oxides depends on the electronegativity of the element and the nature of the oxide.
• Oxides of metals generally tend to be basic, whereas oxides of non-metals tend to be acidic.
• The basic nature of an oxide increases as we move down a group in the periodic table, because the metallic character increases.
• The basicity of an oxide also increases as the oxidation state of the metal decreases. Lower oxidation states tend to form more basic oxides.

EXPLANATION:

•  
  • Sb₂O₃ (Antimony(III) oxide): Antimony is a post-transition metal, and the oxide is moderately basic.
  • Bi₂O₃ (Bismuth(III) oxide): Bismuth is a heavier post-transition metal, and its oxide is also basic but less so compared to Sb₂O₃.
  • SeO₂ (Selenium dioxide): Selenium is a non-metal, and its oxide is acidic in nature.
  • Al₂O₃ (Aluminum oxide): Aluminum is a metal, and its oxide is amphoteric, meaning it can act both as an acid and as a base depending on the conditions.
• Among the given oxides, Bi₂O₃ is most basic, as it is from a metal with a lower oxidation state and is less acidic or amphoteric compared to the others.

Therefore, Bi₂O₃ is the most basic oxide among the given options.

The correct answer is Fractional distillation.

Key Points

• Industrially, dioxygen is obtained from the air by first removing carbon dioxide and water vapor, and then, the remaining gases are liquefied and fractionally distilled to give dinitrogen and dioxygen.
• Atmospheric air consists mostly of nitrogen and oxygen - 78% nitrogen, 21% oxygen and the remaining 1% other gases including argon, carbon dioxide, neon, helium, and hydrogen.

Important Points

Fractional distillation: 

• ​​​Atmospheric air is first cooled to -181°C. Oxygen liquefies at this point.
• Since, the boiling point of Nitrogen is -196°C, it remains in a gaseous state.
• But Argon has a boiling point similar to that of oxygen (–186°C) and hence a significant amount of Argon liquifies along with Oxygen.
• The resultant mixture of Oxygen and Argon is drained, decompressed, and passed through a second low-pressure distillation vessel for further purification.
• We then get the output as final purified liquid oxygen, which is then transported using cryogenic containers.

Additional Information

Simple distillation:

• It is a procedure by which two liquids with different boiling points can be separated. Large difference (greater than 25° C) in the boiling points of liquid
• Vacuum distillation is used when the boiling point of the compound is too high (Tb>150oC) in order to distill the compound without significant decomposition.

Concept:

Oxoacids are basically the acids that contain oxygen. Sulphur is known to form many oxoacids. In oxoacids of sulphur, Sulphur exhibits a tetrahedral structure when coordinated to oxygen. Generally, oxoacids of sulphur contain at least one S=O bond and one S-OH bond. Terminal peroxide groups, terminal S=S, terminal and bridging oxygen atoms and chains of (-S-)_n are also observed in addition to S=S and S-OH.

H₂S₂O₃ is called as Thiosulfuric acid. The oxidation number is −2 (for the terminal sulphur), +6 (for the central atom). Since sulphur contains bond between sulphur atoms.

H₂S₂O₄ is called as Dithionous acid. The oxidation number is +3 and the structure has two sulphur bonding between each other.

H₂S₄O₆ is called as polythionic acid. The oxidation number is 0 (for the bridging S atoms), +5 (for the terminal central S atoms). It also contains sulphur bond between them.

H₂S₂O₇ does not show bonding between sulphur atoms.

Pyrosulphuric acid (H₂S₂O₇) is also known as oleum. It is an anhydride of sulphuric acid, it is a colourless, crystalline solid and has a melting point of 36°C. It can be prepared by reacting excess sulphur trioxide with sulphuric acid. The reaction goes like this:

H₂SO₄ + SO₃ → H₂S₂O₇

It reacts with bases to form salts which are called pyrosulphates.

Pyro sulphuric acid (H₂S₂O₇) is a strong acid which is a main constituent of fuming sulfuric acid (oleum). It is also commonly known as disulphuric acid.

Thermal stability of group-16 hydrides decreases from H₂O to H₂Po due to decrease in bond dissociation energy.

The thermal stability of hydrides decreases as we move down within a group in the periodic table. This is primarily due to the increasing size of the central atom, which weakens the bond strength between the atom and hydrogen as you move from top to bottom in a group. For group 16 (the chalcogens), water (H₂O) is an anomaly due to its unique hydrogen-bonding capabilities, making it significantly more thermally stable than other hydrides in the same group. Thus, for the given hydrides, the order from least to most thermally stable, considering periodic trends and anomalous behavior of water, would be:

So, correct order of thermal stability is H₂O > H₂S > H₂Se > H₂Te > H₂Po 

Concept:

When hydrogen sulfide (H₂S) gas is passed through an acidic solution containing various metal cations, the solubility product (K_sp) values and sulfide solubility play key roles in determining which sulfides precipitate:

• Cu²⁺ (Copper ion): Forms CuS, which is insoluble in acidic solutions (very low K_sp).

• Pb²⁺ (Lead ion): Forms PbS, which is also insoluble in acidic solutions (very low K_sp).

• Zn²⁺ (Zinc ion): Forms ZnS, but ZnS is soluble in acidic solutions due to a relatively higher K_sp.

Explanation:

The solubility products of different metal sulfides help determine their precipitation in acidic medium:

• CuS: Copper(II) sulfide has a very low K_sp and precipitates even in acidic conditions.

• PbS: Lead(II) sulfide also has a very low K_sp and precipitates in acidic conditions.

• ZnS: Zinc sulfide has a higher K_sp, meaning it is more soluble in acidic solutions and does not readily precipitate when H₂S is passed through the acidic solution.

Conclusion:

Given the solubility factors in acidic conditions, the precipitate will contain: CuS and PbS

Thermal stability of group-16 hydrides decreases from H2O to H2Po due to decrease in bond dissociation energy.

So, correct order of thermal stability is:

H₂O > H₂S > H₂Se > H₂Te > H₂Po 

CONCEPT:

Oxidation State of Sulphur

• The oxidation state (O.S.) of an element in a compound is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic.
• The oxidation state of sulphur can be determined based on the known oxidation states of other elements in the compound and the overall charge of the compound.

EXPLANATION:

• For each compound, the oxidation state of sulphur is determined as follows:
  • SO3: Sulphur is in +6 oxidation state.
  • H2SO3: Sulphur is in +4 oxidation state.
  • SOCl2: Sulphur is in +4 oxidation state.
  • SF4: Sulphur is in +4 oxidation state.
  • BaSO4: Sulphur is in +6 oxidation state.
  • H2S2O7: Both sulphur atoms are in +6 oxidation state.
• We identify the compounds where sulphur is in the +4 oxidation state:
  • H2SO3: +4
  • SOCl2: +4
  • SF4: +4
• Thus, there are 3 compounds with +4 oxidation state of sulphur.

Therefore, the number of compounds with +4 oxidation state of sulphur is 3.

Concept:
Oxyacids of sulfur are compounds where sulfur is bonded to oxygen and hydrogen, and they differ in the oxidation state of sulfur based on the number of oxygen atoms attached.

Explanation:

• Peroxodisulfuric acid: In H₂S₂O₈, sulfur is in the +6 oxidation state.

• Thiosulfuric acid: In H₂S₂O₃, one sulfur is in the +4 oxidation state, and the other is in the -2 state. However, the average oxidation state of sulfur in this compound is +2.

• Dithionic acid: In H₂S₂O₆, sulfur is in the +5 oxidation state.

• Sulfurous acid: In H₂SO₃, sulfur is in the +4 oxidation state.

• Polythionic acid: In H₂S_nO₆, the average oxidation state depends on the number of sulfur atoms, but it can vary between +1 and +2.

• Sulfuric acid: In H₂SO₄, sulfur is in the +6 oxidation state.

Conclusion:
The correct matching is (A) - (vi), (B) - (v), (C) - (iii), (D) - (ii), (E) - (v), (F) - (i)