Chemistry

The p-Block Elements.

Question:

Why is the reactivity of nitrogen different from that of phosphorus?

Answer:

 Molecular nitrogen exists as a diatomic molecule (N2) in which the two nitrogen atoms are linked to each other by triple bond (N≡N). It is a gas at room temperature. Multiple bonding is not possible in case of phosphorus due to its large size. It exists as P4 molecule (solid) in which P atoms are linked to one another by single covalent bonds. Because of greater bond dissociation enthalpy (946 kJ mol-1) of N≡N bond, molecular nitrogen is very less reactive as compared to molecular phosphorus.

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The p-Block Elements.

Q 1.

Give the reason for bleaching action of Cl2.

Q 2.

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

Q 3.

Why are halogens strong oxidising agents?

Q 4.

Match the formulas of oxides given in Column I with the type of oxide given in Column II and mark the correct option.
ncert-exemplar-problems-class-12-chemistry-p-block-elements-47

Q 5.

 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 6.

Describe the manufacture of H2SO4 by contact process?

Q 7.

How does ammonia react with a solution of Cu2+?

Q 8.

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

Q 9.

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

Q 10.

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

Q 11.

Give the resonating structures of N02 and N2O5.

Q 12.

Which of the following acid forms three series of salts?
(a) H2PO2  (b) H3BO3 (C)H3PO4(d)H3PO3

Q 13.

How is O3 estimated quantitatively?

Q 14.

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

Q 15.

Write two uses of ClO2

Q 16.

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 17.

 Why is N2 less reactive at room temperature?

Q 18.

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

Q 19.

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

Q 20.

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

Q 21.

How is the presence of SO2 detected ?

Q 22.

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

Q 23.

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

Q 24.

If chlorine gas is passed through hot NaOH solution, two changes are observed in the oxidation number of chlorine during the reaction. These are —— and ——-

Q 25.

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 26.

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

Q 27.

 Why does R3P=0 exist but R3N=0 does not (R is an alkyl group) ?

Q 28.

Which aerosols deplete ozone?

Q 29.

Why is N2 less reactive at room temperature?

Q 30.

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

Q 31.

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 32.

Why does nitrogen show catenation properties less than phosphorus?

Q 33.

A brown ring is formed in the ring test for NO3 ion. It is due to the formation of
ncert-exemplar-problems-class-12-chemistry-p-block-elements-10

Q 34.

Which of the following options are not in accordance with the properly mentioned against them?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-20

Q 35.

In which of the following reactions cone. H2S04 is used as an oxidizing reagent?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-25

Q 36.

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

Q 37.

 What happens when PCl5 is heated?

Q 38.

Why does O3 act as a powerful oxidising agent?

Q 39.

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

Q 40.

Give two examples to show the anomalous behaviour of fluorine.

Q 41.

Name two poisonous gases which can be prepared from chlorine gas

Q 42.

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

Q 43.

How is ammonia manufactured industrially?

Q 44.

Why is dioxygen a gas but sulphur a solid?

Q 45.

 How is SO2 an air pollutant?

Q 46.

Explain why fluorine forms only one oxoacid, HOF.

Q 47.

 Write two uses of ClO2

Q 48.

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

Q 49.

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

Q 50.

 Why do noble gases have comparatively large atomic size?