Chemistry

The p-Block Elements.

Question:

Which of the following statements are correct?
(a) S – S bond is present in H2S2O6.
(b) In peroxosulphuric acid (H2SO5) sulphur is in +6 oxidation state.
(c) Iron powder along with Al2O3 and K2O is used as a catalyst in the preparation of NH3 by Haber's process
(d) Change in enthalpy is positive for the preparation of SO3 by catalytic oxidation of SO2.

Answer:

(a, b)
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The p-Block Elements.

Q 1.

List the important sources of sulphur.

Q 2.

How is O3 estimated quantitatively?

Q 3.

Why is Ka2 « Ka1 for H2SO4 in water?

Q 4.

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

Q 5.

How is ammonia manufactured industrially?

Q 6.

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 7.

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

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.
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Q 9.

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

Q 10.

 Describe the manufacture of H2SO4 by contact process?

Q 11.

 How is SO2 an air pollutant?

Q 12.

What is the basicity of H3PO4?

Q 13.

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

Q 14.

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

Q 15.

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

Q 16.

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 17.

Mention the conditions required to maximise the yield of ammonia.

Q 18.

 What happens when PCl5 is heated?

Q 19.

Mention three areas in which H2SO4 plays an important role.

Q 20.

Sea is the greatest source of some halogens. Comment.

Q 21.

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

Q 22.

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

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.

Which aerosols deplete ozone?

Q 25.

Why does O3 act as a powerful oxidising agent?

Q 26.

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.

Q 27.

Match the items of Column I and Column II and mark the correct option.
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Q 28.

 Why is N2 less reactive at room temperature?

Q 29.

How does ammonia react with a solution of Cu2+?

Q 30.

 What is the covalence of nitrogen in N2O5 ?

Q 31.

How is ammonia manufactured industrially?

Q 32.

 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 33.

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

Q 34.

Why does the reactivity of nitrogen differ from phosphorus?

Q 35.

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

Q 36.

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 37.

Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidizing power.
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Q 38.

Why does O3 act as a powerful oxidising agent?

Q 39.

Give the disproportionation reaction of H3 P03.

Q 40.

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

Q 41.

Why are halogens coloured?

Q 42.

 How are XeOand XeOF4prepared?

Q 43.

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

Q 44.

How are xenon fluorides XeF2, XeF4 and XeF6  obtained?

Q 45.

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
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Q 46.

Bond dissociation enthalpy of E – H (E = element) bonds is given below. Which of the compounds will act as strongest reducing agent?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-7

Q 47.

On heating with concentrated NaOH solution in an inert atmosphere of CO2, white phosphorus gives a gas. Which of the following statement is incorrect about the gas?
(a) It is highly poisonous and has smell like rotten fish.
(b) Its solution in water decomposes in the presence of light.
(c) It is more basic than NH3  
(d) It is less basic than NH3

Q 48.

A brown ring is formed in the ring test for NO3 ion. It is due to the formation of
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Q 49.

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 50.

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