Chemistry

The p-Block Elements.

Question:

 What is the covalence of nitrogen in N2O5 ?

Answer:

 In N2O5 , each N-atom has four shared pairs of e-1 s as shown:
NCERT Solutions For Class 12 Chemistry Chapter 7 The p Block Elements Textbook Questions Q6

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The p-Block Elements.

Q 1.

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

Q 2.

Why are halogens strong oxidising agents?

Q 3.

 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 4.

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

Q 5.

Give the resonating structures of N02 and N2O5.

Q 6.

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 7.

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

Q 8.

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 9.

Give the reason for bleaching action of Cl2.

Q 10.

Why is N2 less reactive at room temperature?

Q 11.

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

Q 12.

How is O3 estimated quantitatively?

Q 13.

How is the presence of SO2 detected ?

Q 14.

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

Q 15.

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

Q 16.

Write two uses of ClO2

Q 17.

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

Q 18.

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 19.

 Why is N2 less reactive at room temperature?

Q 20.

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

Q 21.

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

Q 22.

How are xenon fluorides XeF2, XeF4 and XeFobtained?

Q 23.

Describe the manufacture of H2SO4 by contact process?

Q 24.

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

Q 25.

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

Q 26.

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

Q 27.

How does ammonia react with a solution of Cu2+?

Q 28.

Name two poisonous gases which can be prepared from chlorine gas

Q 29.

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

Q 30.

Which aerosols deplete ozone?

Q 31.

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

Q 32.

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

Q 33.

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

Q 34.

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

Q 35.

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

Q 36.

In qualitative analysis when H2S is passed through an aqueous solution of salt acidified with dil. HCl, a black precipitate is obtained. On boiling the precipitate with dil. HNO3, it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution gives
ncert-exemplar-problems-class-12-chemistry-p-block-elements-3

Q 37.

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 38.

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 39.

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 40.

Give an example to show the effect of concentration of nitric acid on the formation of oxidation product.

Q 41.

Give two examples to show the anomalous behaviour of fluorine.

Q 42.

Why is ICI more reactive than l2?

Q 43.

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

Q 44.

Give the resonating structures of N02 and N2O5.

Q 45.

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

Q 46.

Why is dioxygen a gas but sulphur a solid?

Q 47.

 Knowing the electron gain enthalpy values of O—>O and O—>O2- as -141 and 702 kJ mol-1 respectively, how can you account for the formation of a large number of oxides having O2- species and not O?

Q 48.

Explain why fluorine forms only one oxoacid, HOF.

Q 49.

 Write two uses of ClO2

Q 50.

 Why do noble gases have comparatively large atomic size?