Chemistry

The p-Block Elements.

Question:

Match the items of Column I and Column II and mark the correct option.
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Answer:

ncert-exemplar-problems-class-12-chemistry-p-block-elements-54

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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.

How is O3 estimated quantitatively?

Q 3.

List the important sources of sulphur.

Q 4.

 Why is N2 less reactive at room temperature?

Q 5.

What is the basicity of H3PO4?

Q 6.

Discuss the general characteristics of Group 15 elements with reference to their electronic configuration, oxidation state, atomic size, ionisation enthalpy and electronegativity.

Q 7.

How is ammonia manufactured industrially?

Q 8.

Out of H2O and H2S, which one has higher bond angle and why?

Q 9.

 What happens when PCl5 is heated?

Q 10.

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

Q 11.

 Discuss the general characteristics of Group 15 elements with reference to their electronic configuration, oxidation state, atomic size, ionisation enthalpy and electronegativity.

Q 12.

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 13.

 Describe the manufacture of H2SO4 by contact process?

Q 14.

 How is SO2 an air pollutant?

Q 15.

 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 16.

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

Q 17.

Match the items of Column I and Column II and mark the correct option.
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Q 18.

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

Q 19.

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

Q 20.

 How are XeOand XeOF4prepared?

Q 21.

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

Q 22.

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

Q 23.

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 24.

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

Q 25.

How are xenon fluorides XeF2, XeF4 and XeF6  obtained?

Q 26.

Mention the conditions required to maximise the yield of ammonia.

Q 27.

How does ammonia react with a solution of Cu2+?

Q 28.

Why does O3 act as a powerful oxidising agent?

Q 29.

Illustrate how copper metal can give different products on reaction with HN03.

Q 30.

Why are halogens coloured?

Q 31.

What happens when PCl5 is heated?

Q 32.

Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidizing power.
ncert-exemplar-problems-class-12-chemistry-p-block-elements-18

Q 33.

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

Q 34.

PCl5 reacts with finely divided silver on heating and a white silver salt is obtained, which dissolves on adding excess aqueous NH3 solution. Write the reactions involved to explain what happens.

Q 35.

 What is the covalence of nitrogen in N2O5 ?

Q 36.

Why is Ka2 « Ka1 for H2SO4 in water?

Q 37.

Sea is the greatest source of some halogens. Comment.

Q 38.

Why is dioxygen a gas but sulphur a solid?

Q 39.

Write the reactions of F2 and Cl2 with water.

Q 40.

Why does O3 act as a powerful oxidising agent?

Q 41.

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

Q 42.

Give the disproportionation reaction of H3 P03 .

Q 43.

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 44.

Write two uses of ClO2

Q 45.

Why are halogens coloured?

Q 46.

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 47.

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 48.

On heating ammonium dichromate and barium azide separately we get
(a) N2 in both cases
(b) N2 with ammonium dichromate and NO with barium azide
(c) N2O  with ammonium dichromate and N2 with barium azide
(d) N2O with ammonium dichromate and N2O with barium azide

Q 49.

Which of the following orders are correct as per the properties mentioned against each?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-23

Q 50.

SF6 is known but SCl6 is not. Why?