Assertion and Reason Questions for Class 11 Chemistry Chapter 11 The p-Block Elements

Assertion and Reason Questions for Class 11 Chemistry Chapter 11 The p-Block Elements

Directions:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

Q.1. Assertion : In carbon dioxide, the carbon is sp³ hybridized.
Reason : CO is a linear monomeric covalent compound.

Answer

Answer:(d) : In CO2, C is sp hybridized. It forms two s bonds with two oxygen atoms and two pp-pp multiple bonds. So CO2 is a linear, monomeric and covalent compound.

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Q.2. Assertion : Compounds formed by nonmetals with metals are covalent in nature.
Reason : Compounds formed between nonmetals themselves are largely covalent.

Answer

Answer:(d) : Compounds formed by non-metals with metals are generally ionic in view of larger differences in their electronegativities. Compounds formed between non-metals themselves are largely covalent in character because of small differences in their electronegativities.

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Q.3. Assertion : The tetrahalides of carbon are not hydrolysed by water under normal conditions.
Reason : Carbon cannot expand its coordination number beyond 4 because of the absence of d-orbitals.

Answer

Answer:(a)

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Q.4. Assertion : All the trihalides of boron act as Lewis acids.

Reason : The relative strength of boron trihalides is of the order BI₃ > BBr₃ > BCl₃ > BF₃

Answer

Answer:(b) : BF3 is weakest Lewis acid.

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Q.5. Assertion : Anhydrous AlCl₃ is covalent but hydrated AlCl₃ is ionic.
Reason : In water, Al₂Cl₆ dissociates into hydrated Al³⁺ and Cl^– ions due to high heat of hydration of these ions.

Answer

Answer:(a)

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Q.6. Assertion : Al forms [AlF₆]^3– but B does not form [BF₆]^3–.
Reason : B does not react with F₂.

Answer

Answer:(c) : B does not have vacant d-orbitals as for B, second shell is the outermost shell.

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Q.7. Assertion : Boron differs from aluminium and other members of group 13 in a number of properties.
Reason : Boron shows anomalous behaviour.

Answer

Answer:(b) : This is due to small atomic size, high electronegativity, high ionization energy and absence of d-orbital of B.

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Q.8. Assertion : The tendency for catenation decreases in the order C > Si > Ge > Sn.
Reason : The catenation depends on the strength of the element-element bond.

Answer

Answer:(a) : As we move down the group 14, the elementelement bond energies decrease rapidly, viz. C–C (355 kJ mol–1), Si–Si (222 kJ mol–1), Ge–Ge (167 kJ mol–1) and Sn–Sn (155 kJ mol–1), so the tendency for catenation decreases in the order C > Si > Ge > Sn.

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