Chemistry

The p-Block Elements.

Question:

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

Answer:

(a) CO2- and NO3 are isoelectronic with 32 electrons and sp2 hybridisation hence trigonal planar structure.

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The p-Block Elements.

Q 1.

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

Q 2.

How is O3 estimated quantitatively?

Q 3.

Discuss the trends in chemical reactivity of group 15 elements.

Q 4.

Mention three areas in which H2SO4 plays an important role.

Q 5.

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

Q 6.

Which aerosols deplete ozone?

Q 7.

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

Q 8.

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

Q 9.

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

Q 10.

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 11.

 What happens when PCl5 is heated?

Q 12.

Write the reactions of F2 and Cl2 with water.

Q 13.

Why is N2 less reactive at room temperature?

Q 14.

Why does nitrogen show catenation properties less than phosphorus?

Q 15.

Give the disproportionation reaction of H3 P03 .

Q 16.

Why are halogens strong oxidising agents?

Q 17.

List the uses of neoirand argon gases.

Q 18.

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 19.

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.

Q 20.

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

Q 21.

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

Q 22.

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

Q 23.

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 24.

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 25.

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

Q 26.

 Why is BiH3 the strongest reducing agent amongst all the hydrides of group 15 elements? (C.B.S.E. 2013)

Q 27.

How does ammonia react with a solution of Cu2+?

Q 28.

 What is the covalence of nitrogen in N2O5 ?

Q 29.

Give two examples to show the anomalous behaviour of fluorine.

Q 30.

Why is ICI more reactive than l2?

Q 31.

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

Q 32.

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

Q 33.

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

Q 34.

 How are XeOand XeOF4prepared?

Q 35.

 Why do noble gases have comparatively large atomic size?

Q 36.

Why is BiH3 the strongest reducing agent amongst all the hydrides of Group 15 elements?

Q 37.

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

Q 38.

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

Q 39.

Why is dioxygen a gas but sulphur a solid?

Q 40.

Which aerosols deplete ozone?

Q 41.

How is SO2 an air pollutant?

Q 42.

Write the reactions of F2 and Cl2 with water.

Q 43.

Give the formula and describe the structure of a noble gas species which is isostructural with:  (i) ICI4 (ii) IBr2 (iii) Br03

Q 44.

On addition of cone. H2SO4 to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because
ncert-exemplar-problems-class-12-chemistry-p-block-elements-1

Q 45.

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 46.

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 47.

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.

Q 48.

Which of the following statements are correct?
(a) All three N – O bond lengths in HNO3 are equal.
(b) All P – Cl bond lengths in PCl5 molecule in gaseous state are equal.
(c) P4  molecule in white phosphorus have angular strain therefore white phosphorus is very reactive.
(d) PCl5 is ionic in solid state in which cation is tetrahedral and anion is octahedral.

Q 49.

In which of the following reactions cone. H2S04 is used as an oxidizing reagent?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-25

Q 50.

Write the structure of pyrophosphoric acid.