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.

previuos
next

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.

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 5.

Mention three areas in which H2SO4 plays an important role.

Q 6.

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

Q 7.

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

Q 8.

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

Q 9.

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

Q 10.

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 11.

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

Q 12.

Which aerosols deplete ozone?

Q 13.

Write the reactions of F2 and Cl2 with water.

Q 14.

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

Q 15.

Why does nitrogen show catenation properties less than phosphorus?

Q 16.

Give the disproportionation reaction of H3 P03 .

Q 17.

Why are halogens strong oxidising agents?

Q 18.

List the uses of neoirand argon gases.

Q 19.

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

Q 20.

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

Q 21.

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 22.

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

Q 23.

 What is the covalence of nitrogen in N2O5 ?

Q 24.

 What happens when PCl5 is heated?

Q 25.

Give two examples to show the anomalous behaviour of fluorine.

Q 26.

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

Q 27.

 Why do noble gases have comparatively large atomic size?

Q 28.

Why is N2 less reactive at room temperature?

Q 29.

Why is H2O a liquid and H2S a gas ?

Q 30.

How is O3 estimated quantitatively?

Q 31.

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

Q 32.

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

Q 33.

Why is dioxygen a gas but sulphur a solid?

Q 34.

Which aerosols deplete ozone?

Q 35.

Write the reactions of F2 and Cl2 with water.

Q 36.

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

Q 37.

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 38.

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 39.

Which of the following is correct for P4 molecule of white phosphorus?
(a) It has 6 lone pairs of electrons (b) It has six P – P single bonds
(c) It has three P – P single bonds (d) It has four lone pairs of electrons,

Q 40.

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 41.

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 42.

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 43.

Why is nitric oxide paramagnetic in gaseous state but the solid obtained on cooling is diamagnetic?

Q 44.

Nitric acid forms an oxide of nitrogen on reaction with P4O10. Write the reaction involved. Also write the resonating structures of the oxide of nitrogen formed.

Q 45.

Match the formulas of oxides given in Column I with the type of oxide given in Column II and mark the correct option.
ncert-exemplar-problems-class-12-chemistry-p-block-elements-47

Q 46.

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 47.

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 48.

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 49.

 Why is N2 less reactive at room temperature?

Q 50.

How does ammonia react with a solution of Cu2+?