Chemistry

The p-Block Elements.

Question:

Mention three areas in which H2SO4 plays an important role.

Answer:

 (i) Sulphuric acid is used for the manufacture of a number of chemicals like hydrochloric acid, phosphoric acid, nitric acid along with a large number of organic compounds.
(ii) A mixture of concentrated nitric acid and concentrated sulphuric acid is used in the manufacture of explosives like picric acid, T.N.T, dynamite etc.
(iii) Dilute solution of acid is employed in petroleum refining in order to remove the unwanted impurities of sulphur.

previuos
next

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.

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

Q 3.

Give the resonating structures of N02 and N2O5.

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

Q 6.

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

Q 7.

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

Q 8.

Why are halogens strong oxidising agents?

Q 9.

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 10.

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 11.

 Why is N2 less reactive at room temperature?

Q 12.

Give the reason for bleaching action of Cl2.

Q 13.

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

Q 14.

How is O3 estimated quantitatively?

Q 15.

How is the presence of SO2 detected ?

Q 16.

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

Q 17.

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

Q 18.

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

Q 19.

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

Q 20.

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

Q 21.

Why is N2 less reactive at room temperature?

Q 22.

Describe the manufacture of H2SO4 by contact process?

Q 23.

Write two uses of ClO2

Q 24.

How does ammonia react with a solution of Cu2+?

Q 25.

Give two examples to show the anomalous behaviour of fluorine.

Q 26.

Which aerosols deplete ozone?

Q 27.

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

Q 28.

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

Q 29.

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

Q 30.

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

Q 31.

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

Q 32.

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 33.

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 34.

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 35.

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

Q 36.

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

Q 37.

Give the resonating structures of N02 and N2O5.

Q 38.

 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 39.

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

Q 40.

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

Q 41.

How can-you prepare Cl2 from HCl and HCl from CI2? Write reactions only.

Q 42.

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 43.

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 44.

In PCl5, phosphorus is in sp3d hybridised state but all its five bonds are not equivalent. Justify your answer with reason.

Q 45.

Assertion (A): Both rhombic and monoclinic sulphur exist as S8 but oxygen exists as OÏ€.
Reason (R): Oxygen forms pπ-pπ multiple bond due to small size and small bond length but pπ-pπ bonding is not possible in sulphur.

Q 46.

 What is the covalence of nitrogen in N2O5 ?

Q 47.

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

Q 48.

How is ammonia manufactured industrially?

Q 49.

Why is dioxygen a gas but sulphur a solid?

Q 50.

Explain why fluorine forms only one oxoacid, HOF.