Chemistry

The p-Block Elements.

Question:

How does ammonia react with a solution of Cu2+?

Answer:

ncert-solutions-for-class-12-chemistry-the-p-block-elements-2

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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.

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

Q 4.

Write the structure of pyrophosphoric acid.

Q 5.

Assertion (A): HNO3 makes from passive.
Reason (R): HNO3 forms a protective layer of ferric nitrate on the surface of iron.

Q 6.

Why is ICI more reactive than l2?

Q 7.

Discuss the trends in chemical reactivity of group 15 elements.

Q 8.

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

Q 9.

 Why do noble gases have comparatively large atomic size?

Q 10.

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

Q 11.

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 [he formation of a large number of oxides having O2- species and not O?

Q 12.

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

Q 13.

Why do noble gases have comparatively large atomic sizes?

Q 14.

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

Q 15.

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 16.

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

Q 17.

Why is helium used in diving apparatus?

Q 18.

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

Q 19.

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 20.

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

Q 21.

 Describe the manufacture of H2SO4 by contact process?

Q 22.

 How is SO2 an air pollutant?

Q 23.

Mention the conditions required to maximise the yield of ammonia.

Q 24.

What is the basicity of H3PO4?

Q 25.

What happens when H3PO4 is heated?

Q 26.

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

Q 27.

Why does the reactivity of nitrogen differ from phosphorus?

Q 28.

Why does R3P = O exist but R3N = O does not (R = alkyl group)?

Q 29.

Give the disproportionation reaction of H3 P03 .

Q 30.

Describe the manufacture of H2SO4 by contact process?

Q 31.

Why are halogens strong oxidising agents?

Q 32.

Write two uses of ClO2

Q 33.

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

Q 34.

Which one of the following does not exist ?
(i)XeOF4 (ii)NeF2
(iii)XeF4 (iv)XeF6

Q 35.

List the uses of neoirand argon gases.

Q 36.

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 37.

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 38.

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 39.

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

Q 40.

PH3 forms bubbles when passed slowly in water but NH3 dissolves. Explain.

Q 41.

SF6 is known but SCl6 is not. Why?

Q 42.

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 43.

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 44.

On heating compound (A) gives a gas (B) which is a constituent of air. This gas when treated with 3 mol of hydrogen (H2   ) in the presence of a catalyst gives another gas (C) which is basic in nature. Gas C on further oxidation in moist condition gives a compound (D) which is a part of acid rain. Identify compounds (A) to (D) and also give necessary equations of all the steps involved. –

Q 45.

Mention the conditions required to maximise the yield of ammonia.

Q 46.

How does ammonia react with a solution of Cu2+?

Q 47.

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

Q 48.

 What happens when PCl5 is heated?

Q 49.

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

Q 50.

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