Chemistry

The p-Block Elements.

Question:

Which of the following statements are correct for SO2  gas?
(a) It acts as a bleaching agent in moist conditions.
(b) Its molecule has a linear geometry.
(c) Its dilute solution is used as disinfectant.
(d) It can be prepared by the reaction of dilute H2SO4 with metal sulphide.

Answer:

(a, c) SO2 acts as a bleaching agent in presence of moisture. This is due to reducing nature of SO2
SO2 + 2H2O ->• H2SO4 + 2H
Coloured matter + H –> colourless matter. Its dilute solution is used as disinfectant.

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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.

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

Q 4.

 Why is N2 less reactive at room temperature?

Q 5.

What is the basicity of H3PO4?

Q 6.

List the important sources of sulphur.

Q 7.

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

Q 8.

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

Q 9.

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 10.

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

Q 11.

 What happens when PCl5 is heated?

Q 12.

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

Q 13.

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

Q 14.

 How is SO2 an air pollutant?

Q 15.

 How are XeOand XeOF4prepared?

Q 16.

 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 17.

How is ammonia manufactured industrially?

Q 18.

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 19.

How are xenon fluorides XeF2, XeF4 and XeF6  obtained?

Q 20.

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

Q 21.

 Describe the manufacture of H2SO4 by contact process?

Q 22.

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

Q 23.

White phosphorus reacts with chlorine and the product hydrolysis in the presence of water. Calculate the mass of HCl obtained by the hydrolysis of the product formed by the reaction of 62 g of white phosphorus with chlorine in the presence of water.

Q 24.

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 25.

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 26.

Why does O3 act as a powerful oxidising agent?

Q 27.

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

Q 28.

Why are halogens coloured?

Q 29.

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

Q 30.

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

Q 31.

Mention the conditions required to maximise the yield of ammonia.

Q 32.

How does ammonia react with a solution of Cu2+?

Q 33.

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

Q 34.

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

Q 35.

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

Q 36.

How is ammonia manufactured industrially?

Q 37.

Why is dioxygen a gas but sulphur a solid?

Q 38.

Write the reactions of F2 and Cl2 with water.

Q 39.

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

Q 40.

What happens when H3PO4 is heated?

Q 41.

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

Q 42.

Why does O3 act as a powerful oxidising agent?

Q 43.

Why does the reactivity of nitrogen differ from phosphorus?

Q 44.

Give the disproportionation reaction of H3 P03 .

Q 45.

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 46.

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

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.

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 49.

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 50.

Assertion (A): NaCl reacts with concentrated H2SO4  to give colourless fumes with pungent smell. But on adding MnO2  the fumes become greenish yellow.
Reason (R): MnO2 oxidises HCl to chlorine gas which is greenish yellow.