Group 15 Elements (Nitrogen Family) MCQ Quiz - Objective Question with Answer for Group 15 Elements (Nitrogen Family) - Download Free PDF

Concept:

Boiling Points: The boiling points of the hydrides of group 15 elements are influenced by molecular weight and intermolecular forces. Generally, the boiling point increases with molecular weight due to stronger van der Waals forces. However, hydrogen bonding can significantly increase the boiling point of lighter hydrides like NH₃.

The Correct Answer is Statements I and II are true but II is not the correct explanation for I. 

Concept:-

Inert Pair Effect- The inert pair effect is a phenomenon observed in certain heavy main group elements, particularly those in groups 13, 14, 15, and 16 of the periodic table.

This effect arises due to the poor shielding effect of inner electrons in heavier elements as a result of which outer s- orbital electron are used for the bonding making the lower oxidation more stable than the higher oxidation state in heavier elements.

E.g.- +2 Oxidation state is more stable than +4 oxidation state in heavier elements of group 14 and +3 oxidation state is more stable than +5 oxidation state of heavier elements of group 15.

Explanation:-

Down the group the stability of +3 oxidation state increases and stability of +5 oxidation state decreases. Thus, AsCl₅ is thermally less stable than PCl₅ due to the inert pair effect in AsCl₅ not due to the bigger size of As.

Conclusion:- 

Thermal stability of AsCl₅ is less than PCl₅ due to inert pair effect.

CONCEPT:

Covalency of Elements

• Covalency refers to the number of covalent bonds an atom can form.
• The maximum covalency of an element is determined by the number of empty orbitals available for bonding and the element's ability to expand its valence shell.

EXPLANATION:

• In the given statement:

  Assertion (A): Nitrogen shows a maximum covalency of 4 whereas phosphorus shows a maximum covalency of 6.

  Reason (R): Nitrogen has higher electronegativity than phosphorus.

• Explanation:
  • Nitrogen (N) has a small atomic size and lacks d-orbitals. Therefore, it can only form a maximum of four covalent bonds (using its s and p orbitals).
  • Phosphorus (P), on the other hand, has empty d-orbitals that can participate in bonding. This allows phosphorus to expand its valence shell and form up to six covalent bonds.
  • Although it is true that nitrogen has higher electronegativity than phosphorus, this is not the reason for the difference in their maximum covalency.

Therefore, the correct answer is (A) is true and (R) is false.

Concept:

The trihalides of nitrogen exhibit different stabilities and reactivity based on the bond strengths and sizes of the halogen atoms attached to nitrogen. The stability and properties of these trihalides can be explained based on their covalent or ionic nature and the size differences between nitrogen and the halogens. The properties of these compounds lead to distinct behaviors, such as stability and reactivity towards hydrolysis.

• NF₃: It is stable and does not undergo hydrolysis with water, dilute acids, or alkalis. The strong N—F bond makes NF₃ an exothermic compound.
• NCl₃: This trihalide is explosive due to the weakness of the N—Cl bond, resulting in instability.
• NBr₃ and NI₃: These trihalides are known as their unstable ammoniates, such as NBr₃·NH₃ and NI₃·NH₃.

Explanation:

• Statement A is correct as NF₃ is stable and does not undergo hydrolysis.
• Statement B is correct since NCl₃ is unstable due to the weak N—X bond.
• Statement C is correct because NBr₃ and NI₃ exist in unstable ammoniate forms.
• Statement D is incorrect because NF₃ is stable, not the least stable among the nitrogen trihalides.

Conclusion: 

The correct statements are A, B, and C.

Concept:

Nature of Oxides of Nitrogen

• Oxides of nitrogen can exhibit different chemical behaviors, such as being acidic, basic, or neutral.
• Neutral oxides are those that do not form acids or bases when dissolved in water, and they do not react with acids or bases to form salts or water.

Explanation:

• N₂O (Nitrous oxide)
  • Neutral. N₂O is a neutral oxide as it does not react with acids or bases.
• NO (Nitric oxide)
  • Neutral. NO is also a neutral oxide and does not exhibit acidic or basic properties.
• NO₂ (Nitrogen dioxide)
  • Incorrect. NO₂ is acidic in nature and forms acids in water.
• N₂O₃ (Dinitrogen trioxide)
  • Incorrect. N₂O₃ is also acidic in nature and forms acids in water.

Conclusion:

The neutral oxides of nitrogen are N₂O (Nitrous oxide) and NO (Nitric oxide).

The correct answer is Nitric acid.

• Nitric acid is used in the purification of gold and silver.

Key Points

• Nitric acid is used in the purification of gold. The acid mixture aqua regia, or royal water, dissolves gold and is used to purify scrap alloy containing gold.
  • Aqua regia is a mixture of hydrochloric acid and nitric acid in a 3:1 ratio.
  • Nitric acid is a nitrogen oxoacid of formula HNO3 in which the nitrogen atom is bonded to a hydroxy group and by equivalent bonds to the remaining two oxygen atoms.

Important Points

The correct answer is CO + N₂

• Producer gas is a mixture of CO + N₂

Key Points

• Producer gas:
  • A typical producer gas obtained from coke contains 27% carbon monoxide, 12% hydrogen, 0.5% methane, 5% carbon dioxide and 55% nitrogen, by volume.
  • Producer gas is fuel gas that is made from material such as coal.
  • A combustible mixture of nitrogen, carbon monoxide, and hydrogen gives the producer gas. 
  • It is the cheapest gaseous fuel; however, its calorific value is not very high because it has a large proportion of nitrogen.
  • It is made by the partial combustion of carbonaceous substances usually coal, in an atmosphere of air and steam. 

Additional Information

• Coal gas is a mixture of H₂, CH₄, CO, and gases like N₂, C₂, H₄, O₂, etc. 
• Oil gas is a mixture of H₂, CH₄, C₂H₄, CO, and other gases like CO₂.
• Syngas, or synthesis gas, is a fuel gas mixture consisting primarily of hydrogen, carbon monoxide, and very often some carbon dioxide. 

The correct answer is Nitric acid.

• Nitric acid is used in the purification of gold and silver.

Key Points

• Nitric acid is used in the purification of gold. The acid mixture aqua regia, or royal water, dissolves gold and is used to purify scrap alloy containing gold.
  • Aqua regia is a mixture of hydrochloric acid and nitric acid in a 3:1 ratio.
  • Nitric acid is a nitrogen oxoacid of formula HNO3 in which the nitrogen atom is bonded to a hydroxy group and by equivalent bonds to the remaining two oxygen atoms.

Important Points

The correct answer is CO + N₂

• Producer gas is a mixture of CO + N₂

Key Points

• Producer gas:
  • A typical producer gas obtained from coke contains 27% carbon monoxide, 12% hydrogen, 0.5% methane, 5% carbon dioxide and 55% nitrogen, by volume.
  • Producer gas is fuel gas that is made from material such as coal.
  • A combustible mixture of nitrogen, carbon monoxide, and hydrogen gives the producer gas. 
  • It is the cheapest gaseous fuel; however, its calorific value is not very high because it has a large proportion of nitrogen.
  • It is made by the partial combustion of carbonaceous substances usually coal, in an atmosphere of air and steam. 

Additional Information

• Coal gas is a mixture of H₂, CH₄, CO, and gases like N₂, C₂, H₄, O₂, etc. 
• Oil gas is a mixture of H₂, CH₄, C₂H₄, CO, and other gases like CO₂.
• Syngas, or synthesis gas, is a fuel gas mixture consisting primarily of hydrogen, carbon monoxide, and very often some carbon dioxide. 

The correct answer is N_2.

Key Points

• NH₄Cl and KNO₂ are reactants which are mixed together in presence of heat.
• The reaction in which heating a mixture of NH₄Cl and KNO₂ is done is as following:

NH₄Cl           +      KNO₂     ------->   N₂ +            KCl         +    2H₂O

Ammoniuum       Potassium            Nitrogen   Potassium         water

    chloride             nitrite                                     chloride

• We can see,  the mixture of NH4Cl and KNO2  is used to produce a super stable nitrogen gas which is used for industrial purposes such as packaging.

Additional Information

• NH4Cl is an explosive substance.
• It reacts violently with the oxidizing agents and produces corrosive gaseous vapours of ammonia and some nitrous vapours also.
• Ammonium chloride is a dangerous chemical substance which creates human health problems such as cough, headache etc. if exposed openly.

A correct answer is option (4).

Key PointsPreparation of dinitrogen:

• Dinitrogen is produced commercially by the liquefaction and fractional distillation of air.
• Liquid dinitrogen (b.p. 77.2 K) distils out first leaving behind liquid oxygen (b.p. 90 K).
• In the laboratory, dinitrogen is prepared by treating an aqueous solution of ammonium chloride with sodium nitrite.
• Very pure nitrogen can be obtained by the thermal decomposition of sodium or barium azide.
• Industrial nitrogen gas is produced by cryogenic fractional distillation of liquefied air, and separation of gaseous air by adsorption, or permeation through membranes.
• Cryogenic distillation of air is the oldest method of nitrogen production and was developed in 1895.

Physical & Chemical properties:

• Dinitrogen is a colourless, odourless, tasteless and non-toxic gas.
• The nitrogen atom has two stable isotopes: ¹⁴N and ¹⁵N.
• It has very low solubility in water and low freezing and boiling point.
• Dinitrogen is rather inert at room temperature because of the high bond enthalpy of the N≡N bond.
• Reactivity increases rapidly with a rise in temperature.
• At higher temperatures, it directly combines with some metals to form predominantly ionic nitrides and with non-metal covalent nitrides. 

Concept:

Oxoacids of phosphorous - 

→Oxoacids are acids containing oxygen.

• Phosphorous forms a number of oxoacids in which phosphorous is tetrahedrally surrounded by other atoms. 
• Thus hybridisation of 'P' in oxoacids of phosphorous is sp3.
• At least one P=O and one P-OH bond is present in all oxoacids, along with that P-H and P-P bonds may or may not be present.

Phosphorous generally forms two types of oxoacids named phosphorous and phosphoric series.

• The P-H bond in oxoacids of phosphorous is not ionisable and hence not acidic.
• The basicity is due to ionisable H+ present in P-OH only.
• Hence, the number of P-OH bond in the oxoacid decide the basicity of the compound.
• The reducing properties of the oxoacids are due to the P-H bonds.

The oxoacids of phosphorous are - 

Explanation:

The given statement is ,"Action of heat on A, a dibasic acid of phosphorous, gives noninflammable hydride of phosphorous B, which becomes inflammable when exposed to air". 

Dibasic acid of phosphorous is phosphorous acid having formula H3PO3.

• On heating phosphorous acid (H3PO3) orthophosphoric acid (H3PO4 )and phosphine (PH3) is obtained.
  • H3PO₃ \(\xrightarrow{\Delta}\) H3PO4 + PH3.
• Phosphine(PH3) is hydride of phosphorous having formula PH3.
• Phosphine(PH3) is non inflammable gas which become inflammable when exposed to air due to presence of impurity P₂H₄.

Conclusion:

Therefore, A and B are - H3PO3 and PH3

Concept:

Nature of Oxides of Nitrogen

• Oxides of nitrogen can exhibit different chemical behaviors, such as being acidic, basic, or neutral.
• Neutral oxides are those that do not form acids or bases when dissolved in water, and they do not react with acids or bases to form salts or water.

Explanation:

• N₂O (Nitrous oxide)
  • Neutral. N₂O is a neutral oxide as it does not react with acids or bases.
• NO (Nitric oxide)
  • Neutral. NO is also a neutral oxide and does not exhibit acidic or basic properties.
• NO₂ (Nitrogen dioxide)
  • Incorrect. NO₂ is acidic in nature and forms acids in water.
• N₂O₃ (Dinitrogen trioxide)
  • Incorrect. N₂O₃ is also acidic in nature and forms acids in water.

Conclusion:

The neutral oxides of nitrogen are N₂O (Nitrous oxide) and NO (Nitric oxide).

CONCEPT:

Abundance of Elements in Oceans and Atomic Size

• Abundance of elements in the earth’s crust and oceans can vary based on different factors, including chemical reactivity and geochemical processes.
• Sodium (Na) is more abundant in the oceans compared to potassium (K) due to its higher chemical reactivity and solubility in water.
• The size of the atom is determined by the number of electron shells. Because potassium is in the fourth period, it has more electron shells compared to sodium, which is in the third period, making the potassium atom larger.

EXPLANATION:

Sodium is the most abundant alkali metal in the earth’s crust. Sodium and potassium are the seventh and eighth most abundant elements by weight in the earth’s crust. Owing to its high reactivity, sodium is found in nature only as a compound and never as the free element.

Potassium atom is in 4th period and sodium is in 3rd period, the number of outermost orbits is greater in potassium than sodium. So, the nuclear attractions decreases in potassium which ultimately leads to the larger size of it.

• Assertion A: True. Sodium is about 30 times as abundant as potassium in the oceans.
• Reason R: True. Potassium is bigger in size than sodium due to having an extra electron shell.
• However, the size of the atoms (Reason R) is not the correct explanation for the abundance of sodium and potassium in the oceans (Assertion A). The abundance is more related to their chemical reactivity and solubility in water rather than the atomic size.

The correct answer is 1) Both A and R are true but R is NOT the correct explanation of A

The Correct Answer is C and D.

Concept:-

NOCl behaves as an electrophile and an oxidant with the halide acceptor in most of its reaction.

BrF₃ is a strong fluorinating agent which is able to convert a metal to its associated fluoride compound.

Explanation:-

(A). NOCl + Sn \(\xrightarrow{ N _2 O _4}\) [NO]⁺ + Cl^- (Not as a major product)

(B). NOCl + AgNO₃ → AgCl + N₂O₄ (Neutralization Reaction) 

(C). NOCl + BrF₃ → [NO]⁺[BrF₃Cl]^-

(D). NOCl + SbCl₅ → [NO]⁺[SbCl₆]^-

Conclusion:-

Reaction C and D which will give [NO]⁺ as a major product.