Assertion and Reason Questions on Class 12 Chemistry Chapter 7 p-BLOCK ELEMENTS (GROUP 15, 16, 17 AND 18)

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.

Q.1. Assertion : Dinitrogen is inert at room temperature.
Reason : Dinitrogen directly combines with lithium to form ionic nitrides.

Answer (c)

Q.2. Assertion : N2 is less reactive than P4.
Reason : Nitrogen has more electron gain enthalpy than phosphorus.

Answer (c)

Q.3. Assertion : When a metal is treated with conc. HNO3 it generally yields a nitrate, NO2 and H2O.
Reason : Conc. HNO3 reacts with metal and first produces a metal nitrate and nascent hydrogen. The nascent hydrogen then further reduces HNO3 to NO2

Answer (a)

Q.4. Assertion : White phosphorus is more reactive than red phosphorus.
Reason : Red phosphorus consists of P4 tetrahedral units linked to one another to form linear chains.

Answer (b) White phosphorus exists as P4 tetrahedral molecule having P-P-P bond angle 60º. Hence the molecule is under strain and more reactive. On the other hand red phosphorus exists as P4 tetrahedra which are joined together through covalent bonds giving polymeric structure.

Q.5. Assertion : Bond angle of H2S is smaller than H2O.
Reason : Electronegativity of the central atom increases, bond angle decreases.

Answer (c)

Q.6. Assertion : Both rhombic and monoclinic sulphur exist as S8 but oxygen exists as O2.
Reason : Oxygen forms pπ – pπ multiple bond due to small size and small bond length but pπ – pπ bonding is not possible in sulphur.

Answer (a)

Q.7. Assertion : SF6 cannot be hydrolysed but SF4 can be.
Reason : Six F atoms in SF6 prevent the attack of H2O on sulphur atom of SF6.

Answer (a)

Q.8. Assertion: Ozone is thermodynamically stable with respect to oxygen.
Reason: Decomposition of ozone into oxygen results in the liberation of heat

Answer (d)

Q.9. Assertion : Inert gases are monoatomic,
Reason : Inert gases have stable configuration.

Answer (a)

Q.10. Assertion : Fluorine exists only in-1 oxidation state.
Reason: Fluorine has 2s22p5 configuration.

Answer (a)

Q.11. Assertion : The fluorine has lower reactivity.
Reason : F-F bond has low bond dissociation energy.

Answer (c)

Q.12. Assertion: F-F bond in F2 molecule is weak.
Reason: F atom is small in size.

Answer (a)

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