Chemistry

The p-Block Elements.

Question:

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).

Answer:

In all these cases, the central atom is sp3 hybridized. Three of the four sp3 orbitals form three σ-bonds, while the fourth contains the lone pair of electrons. On moving down from N to Sb, the electronegativity of the central atom goes on decreasing. As a result of this, bond  pairs of electrons lie away and away from the central atom. This is because of the force of repulsion between the adjacent bond pairs goes on decreasing and the bond angles keep on decreasing from NH3 to SbH3. Thus, bond angles are in the order:
NCERT Solutions For Class 12 Chemistry Chapter 7 The p Block Elements Exercises Q9

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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.

How is O3 estimated quantitatively?

Q 3.

List the important sources of sulphur.

Q 4.

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

Q 5.

 Why is N2 less reactive at room temperature?

Q 6.

What is the basicity of H3PO4?

Q 7.

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

Q 8.

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

Q 9.

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

Q 10.

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 11.

 How is SO2 an air pollutant?

Q 12.

 Arrange the following in the order of property indicated for each set: –
(i) F2 , Cl2 , Br2 , I2 – increasing bond dissociation enthalpy.
(ii) HF, HCI, HBr, HI – increasing acid . strength.
(iii) NH3, PH3, AsH3, SbH3, BiH3 – increasing Sol. base strength.

Q 13.

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

Q 14.

How is ammonia manufactured industrially?

Q 15.

What inspired N. Bartlett for carrying out reaction between Xe and PtF6?

Q 16.

 What happens when PCl5 is heated?

Q 17.

Why are halogens coloured?

Q 18.

How are xenon fluorides XeF2, XeF4 and XeF6  obtained?

Q 19.

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 20.

Match the items of Column I and Column II and mark the correct option.
ncert-exemplar-problems-class-12-chemistry-p-block-elements-49
ncert-exemplar-problems-class-12-chemistry-p-block-elements-50

Q 21.

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

Q 22.

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

Q 23.

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

Q 24.

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

Q 25.

 Describe the manufacture of H2SO4 by contact process?

Q 26.

Write the reactions of F2 and Cl2 with water.

Q 27.

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

Q 28.

 How are XeOand XeOF4prepared?

Q 29.

What happens when H3PO4 is heated?

Q 30.

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

Q 31.

Why does O3 act as a powerful oxidising agent?

Q 32.

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 33.

Give the disproportionation reaction of H3 P03 .

Q 34.

What are the oxidation states of phosphorus in  the following: –
(i) H3PO3 (ii)PCl3
(iii) Ca3P2(iv)Na3PO4
(v) POF3

Q 35.

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

Q 36.

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 37.

Mention the conditions required to maximise the yield of ammonia.

Q 38.

How does ammonia react with a solution of Cu2+?

Q 39.

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

Q 40.

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

Q 41.

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

Q 42.

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

Q 43.

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

Q 44.

Why is dioxygen a gas but sulphur a solid?

Q 45.

 Why are halogens strong oxidising agents?

Q 46.

Explain why fluorine forms only one oxoacid, HOF.

Q 47.

 Which one of the following does not exist ?
(i)XeOF4 (ii)NeF2
(iii)XeF4 (iv)XeF6

Q 48.

 Why do noble gases have comparatively large atomic size?

Q 49.

Mention the conditions required to maximise the yield of ammonia.

Q 50.

How does ammonia react with a solution of Cu2+?