Chemistry

The p-Block Elements.

Question:

Write two uses of ClO2

Answer:

(1) ClO2 is an excellent bleaching agent. It is 30 times stronger bleaching agent then the Cl2. It is used as a bleaching agerit for paper pulp in paper industry and in textile industry. (2) ClO2 is also a powerful oxidising agent and chlorinating agent. It acts as a germicide for disinfecting water. It is used for purifying drinking water.

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The p-Block Elements.

Q 1.

Discuss the trends in chemical reactivity of group 15 elements.

Q 2.

How is O3 estimated quantitatively?

Q 3.

Mention three areas in which H2SO4 plays an important role.

Q 4.

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

Q 5.

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

Q 6.

List the uses of neoirand argon gases.

Q 7.

In the preparation of H2S06 by contact process, why is S03 not absorbed directly in water to form H2S04?

Q 8.

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

Q 9.

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

Q 10.

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

Q 11.

Which aerosols deplete ozone?

Q 12.

Write the reactions of F2 and Cl2 with water.

Q 13.

Mention three areas in which H2SO4 plays an important role.

Q 14.

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

Q 15.

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

Q 16.

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

Q 17.

Why are halogens strong oxidising agents?

Q 18.

Write the structure of pyrophosphoric acid.

Q 19.

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

Q 20.

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 21.

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 22.

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 23.

Assertion (A): HI cannot be prepared by the reaction of KI with concentrated H2SO4.
Reason (R): HI has lowest H – X bond strength among halogen acids.

Q 24.

 Why is N2 less reactive at room temperature?

Q 25.

Why is bond angle in PH+4 ion higher than in PH3 ? (Pb. Board 2009)

Q 26.

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

Q 27.

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

Q 28.

Give the reason for bleaching action of Cl2.

Q 29.

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

Q 30.

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

Q 31.

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

Q 32.

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 33.

 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 34.

 Arrange the following in the order of property indicated for each set: –
(i) F2 , Cl2 , Br2 , I2 – increasing bond dissociation enthalpy.
(ii) HF, HCI, HBr, HI – increasing acid . strength.
(iii) NH3, PH3, AsH3, SbH3, BiH3 – increasing Sol. base strength.

Q 35.

 List the uses of neoirand argon gases.

Q 36.

Why is N2 less reactive at room temperature?

Q 37.

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

Q 38.

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

Q 39.

How is the presence of SO2 detected ?

Q 40.

Give the resonating structures of N02 and N2O5.

Q 41.

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 42.

Which aerosols deplete ozone?

Q 43.

How is SO2 an air pollutant?

Q 44.

Explain why fluorine forms only one oxoacid, HOF.

Q 45.

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 46.

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

Q 47.

How are XeO3  and XeOF4prepared?

Q 48.

Which of the following pairs of ions are isoelectronic and isostructural?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-6

Q 49.

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 50.

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.