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 the reactions of F2 and Cl2 with water.

Q 2.

Match the formulas of oxides given in Column I with the type of oxide given in Column II and mark the correct option.
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Q 3.

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

Q 4.

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

Q 5.

Why are halogens coloured?

Q 6.

Match the compounds given in Column I with the hybridization and shape given in Column II and mark the correct option.
ncert-exemplar-problems-class-12-chemistry-p-block-elements-44

Q 7.

 Write two uses of ClO2

Q 8.

 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 9.

Write a balanced equation for the hydrolytic reaction of PC is in heavy water.

Q 10.

How is the presence of SO2 detected ?

Q 11.

Give the resonating structures of N02 and N2O5.

Q 12.

Write two uses of ClO2

Q 13.

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

Q 14.

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

Q 15.

 Why is BiH3 the strongest reducing agent amongst all the hydrides of group 15 elements? (C.B.S.E. 2013)

Q 16.

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

Q 17.

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

Q 18.

 Why does nitrogen show catenation properties less than phosphorus ? (C.B.S.E. Foreign 2009)

Q 19.

Why is dioxygen a gas but sulphur a solid?

Q 20.

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

Q 21.

List the uses of neoirand argon gases.

Q 22.

Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidizing power.
ncert-exemplar-problems-class-12-chemistry-p-block-elements-18

Q 23.

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 24.

Give reason to explain why ClF3 exists but FCl3 does not exist.

Q 25.

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

Q 26.

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

Q 27.

Explain why inspite of nearly the same electronegativity, nitrogen forms hydrogen bonding while chlorine does not.

Q 28.

 List the uses of neoirand argon gases.

Q 29.

Why is BiH3 the strongest reducing agent amongst all the hydrides of Group 15 elements?

Q 30.

Why is N2 less reactive at room temperature?

Q 31.

List the important sources of sulphur.

Q 32.

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

Q 33.

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

Q 34.

How is O3 estimated quantitatively?

Q 35.

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

Q 36.

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

Q 37.

Mention three areas in which H2SO4 plays an important role.

Q 38.

Why does NH3 form hydrogen bond but PH3 does not?

Q 39.

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

Q 40.

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

Q 41.

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

Q 42.

Why are halogens strong oxidising agents?

Q 43.

Explain why fluorine forms only one oxoacid, HOF.

Q 44.

Write the reactions of F2 and Cl2 with water.

Q 45.

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

Q 46.

With what neutral molecule is CIO isoelectronic? Is that molecule a Lewis base?

Q 47.

How are XeO3  and XeOF4prepared?

Q 48.

Give the formula and describe the structure of a noble gas species which is isostructural with:  (i) ICI4 (ii) IBr2 (iii) Br03

Q 49.

Why do noble gases have comparatively large atomic sizes?

Q 50.

On addition of cone. H2SO4 to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because
ncert-exemplar-problems-class-12-chemistry-p-block-elements-1