Chemistry

The p-Block Elements.

Question:

Assertion (A): Both rhombic and monoclinic sulphur exist as S8 but oxygen exists as OÏ€.
Reason (R): 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) S exists as S8  but oxygen exists as O2 because oxygen forms pÏ€-pÏ€ multiple bonds which is not possible in S.

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The p-Block Elements.

Q 1.

Write balanced equations for the following:
(i) NaCl is heated witlrsulphuric acid in the presence of MnO2
(ii) Chlorine gas is passed into a solution of Nal in water.

Q 2.

Discuss the general characteristics of Group 15 elements with reference to their electronic configuration, oxidation state, atomic size, ionisation enthalpy and electronegativity.

Q 3.

 Why is N2 less reactive at room temperature?

Q 4.

List the important sources of sulphur.

Q 5.

White phosphorus reacts with chlorine and the product hydrolysis in the presence of water. Calculate the mass of HCl obtained by the hydrolysis of the product formed by the reaction of 62 g of white phosphorus with chlorine in the presence of water.

Q 6.

How is O3 estimated quantitatively?

Q 7.

Comment on the nature of two S-O bonds formed in S02 molecule. Are the two S-O bonds in this molecule equal ?

Q 8.

 How is nitrogen prepared in the laboratory? Write the chemical equations of the reactions . involved.

Q 9.

What is the basicity of H3PO4?

Q 10.

How is ammonia manufactured industrially?

Q 11.

PCl5 reacts with finely divided silver on heating and a white silver salt is obtained, which dissolves on adding excess aqueous NH3 solution. Write the reactions involved to explain what happens.

Q 12.

Illustrate how copper metal can give different products on reaction with HN03.

Q 13.

The HNH angle value is higher than HPH, H AsH and HSbH angles. Why?
(Hint: Can be explained on the basis of sp3 hybridisation in NH3 and only s-p bonding , between hydrogen and other elements of the group).

Q 14.

Which of the following does not react with oxygen directly?  Zn, Ti, Pt, Fe

Q 15.

Complete the following reactions:
(i)C2H2  + O2 -> (ii) 4Al + 3 O2 ->

Q 16.

Out of H2O and H2S, which one has higher bond angle and why?

Q 17.

 What happens when PCl5 is heated?

Q 18.

 Write the order of thermal stability of the – hydrides of Group 16 elements.

Q 19.

Write the conditions to maximise the yield of H2SO4 by Contact process.

Q 20.

Considering the parameters such as bond dissociation enthalpy, electron gain enthalpy and hydration enthalpy, compare the oxidising powers of F2 and Cl2.

Q 21.

 Discuss the general characteristics of Group 15 elements with reference to their electronic configuration, oxidation state, atomic size, ionisation enthalpy and electronegativity.

Q 22.

Explain why NH3 is basic while BiH3 is only feebly basic.

Q 23.

 How is SO2 an air pollutant?

Q 24.

 Why are halogens strong oxidising agents?

Q 25.

Why are halogens coloured?

Q 26.

 With which neutral molecule is ClO isoelectronic? Is this molecule Lewis acid or base ? (Pb. Board 2009)

Q 27.

 How are XeOand XeOF4prepared?

Q 28.

Mention the conditions required to maximise the yield of ammonia.

Q 29.

Give the resonating structures of N02 and N2O5.

Q 30.

The HNH angle value is higher than HPH, H AsH and HSbH angles. Why?
(Hint: Can be explained on the basis of sp3 hybridisation in NH3 and only s-p bonding , between hydrogen and other elements of the group).

Q 31.

Nitrogen exists as diatomic molecule and phosphorus as P4. Why?

Q 32.

Give the disproportionation reaction of H3 P03 .

Q 33.

Can PCl5 act as an oxidising as well as a reducing agent Justify.

Q 34.

Describe the manufacture of H2SO4 by contact process?

Q 35.

Write the reactions of F2 and Cl2 with water.

Q 36.

Which of the following statements are correct?
(a) All three N – O bond lengths in HNO3 are equal.
(b) All P – Cl bond lengths in PCl5 molecule in gaseous state are equal.
(c) P4  molecule in white phosphorus have angular strain therefore white phosphorus is very reactive.
(d) PCl5 is ionic in solid state in which cation is tetrahedral and anion is octahedral.

Q 37.

Which of the following orders are correct as per the properties mentioned against each?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-23

Q 38.

Which of the following statements are true?
(a) Only type of interactions between particles of noble gases are due to weak dispersion forces.
(b) Ionisation enthalpy of.molecular oxygen is very close to that of xenon.
(c) Hydrolysis of XeF6 is a redox reaction.
(d) Xenon fluorides are not reactive.

Q 39.

Write a balanced chemical equation, for the reaction showing catalytic oxidation of NH3 by atmospheric oxygen.

Q 40.

Explain why ozone is thermodynamically less stable than oxygen.

Q 41.

P4O6 reacts with water according to equation P4O6 + 6H2O Calculate the volume of 0.1 M NaOH solution required to neutralize the acid formed by dissolving 1.1 g of P4O6 in H2O.

Q 42.

Mention the conditions required to maximise the yield of ammonia.

Q 43.

How does ammonia react with a solution of Cu2+?

Q 44.

 Which of the following does not react with oxygen directly? Zn, Ti, Pt, Fe

Q 45.

What happens when sulp’hur dioxide is passed through an aqueous solution of Fe(III) salt?

Q 46.

Give two examples to show the anomalous behaviour of fluorine.

Q 47.

Why has it been difficult to study the chemistry of radon?

Q 48.

Why does NH3 form hydrogen bond but PH3 does not?

Q 49.

Give the resonating structures of N02 and N2O5.

Q 50.

 Describe the manufacture of H2SO4 by contact process?