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.

How is O3 estimated quantitatively?

Q 2.

Name three oxoacids of nitrogen. Write the disproportionation reaction of that oxoacid of nitrogen in which nitrogen is in +3 oxidation state.

Q 3.

Explain why does the stability of oxoacids of chlorine increase in the order given below:
HClO < HClO2 < HClO3 < HClO4

Q 4.

Discuss the trends in chemical reactivity of group 15 elements.

Q 5.

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 6.

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

Q 7.

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

Q 8.

Why does nitrogen show catenation properties less than phosphorus?

Q 9.

Assertion (A): HNO3 makes from passive.
Reason (R): HNO3 forms a protective layer of ferric nitrate on the surface of iron.

Q 10.

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

Q 11.

 What happens when white phosphorus is heated with concentrated NaOH solution in an inert atmosphere of CO2?

Q 12.

Justify the placement of O, S, Se, Te and Po in the same group’of the periodic table in terms of electronic configuration, oxidation state and hydride formation.

Q 13.

Explain why fluorine forms only one oxoacid, HOF.

Q 14.

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

Q 15.

Which of the following statements are correct?
(a) Among halogens, radius ratio between iodine and fluorine is maximum.
(b) Leaving F – F bond, all halogens have weaker X – X bond than X – X’ bond in interhalogens.
(c) Among interhalogen compounds maximum number of atoms ate present in iodine fluoride.
(d) Interhalogen compounds are more reactive than halogen compounds.

Q 16.

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 17.

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

Q 18.

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

Q 19.

Give two examples to show the anomalous behaviour of fluorine.

Q 20.

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

Q 21.

 How are XeOand XeOF4prepared?

Q 22.

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

Q 23.

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

Q 24.

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

Q 25.

Write main differences between the properties of white phosphorus and red phosphorus.

Q 26.

Explain why fluorine forms only one oxoacid, HOF.

Q 27.

Which of the following is correct for P4 molecule of white phosphorus?
(a) It has 6 lone pairs of electrons (b) It has six P – P single bonds
(c) It has three P – P single bonds (d) It has four lone pairs of electrons,

Q 28.

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

Q 29.

Phosphorus forms a number of oxoacids. Out of these oxoacids phosphinic acid has strong reducing property. Write its structure and also write a reaction showing its reducing behaviour.

Q 30.

An amorphous solid "A"bums in air to form a gas "B"which turns lime water milky. The gas is also produced as a by-product during roasting of sulphide ore. This gas decolourises acidified aqueous KMnO4  solution and reduces Fe3+ to Fe+2. Identify the solid "A"and the gas "B"and write the reactions involved.

Q 31.

 Why is N2 less reactive at room temperature?

Q 32.

 What is the covalence of nitrogen in N2O5 ?

Q 33.

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

Q 34.

What is the basicity of H3PO4?

Q 35.

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

Q 36.

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

Q 37.

Why is dioxygen a gas but sulphur a solid?

Q 38.

 Why do noble gases have comparatively large atomic size?

Q 39.

 List the uses of neoirand argon gases.

Q 40.

Why is N2 less reactive at room temperature?

Q 41.

What is the covalence of nitrogen in N2O5 ?

Q 42.

Bond angle in PH4+ is higher than that in PH3. Why?

Q 43.

How is O3 estimated quantitatively?

Q 44.

Why does the reactivity of nitrogen differ from phosphorus?

Q 45.

Why does R3P = O exist but R3N = O does not (R = alkyl group)?

Q 46.

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

Q 47.

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

Q 48.

Why is dioxygen a gas but sulphur a solid?

Q 49.

How are xenon fluorides XeF2, XeF4 and XeF6  obtained?

Q 50.

How are XeO3  and XeOF4prepared?