Chemistry

The p-Block Elements.

Question:

What happens when PCl5 is heated?

Answer:

ncert-solutions-for-class-12-chemistry-the-p-block-elements-5

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The p-Block Elements.

Q 1.

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 2.

Give the reason for bleaching action of Cl2.

Q 3.

 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 4.

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

Q 5.

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

Q 6.

Why are halogens strong oxidising agents?

Q 7.

How is O3 estimated quantitatively?

Q 8.

Give the resonating structures of N02 and N2O5.

Q 9.

Describe the manufacture of H2SO4 by contact process?

Q 10.

How does ammonia react with a solution of Cu2+?

Q 11.

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

Q 12.

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

Q 13.

How is the presence of SO2 detected ?

Q 14.

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

Q 15.

Which of the following acid forms three series of salts?
(a) H2PO2  (b) H3BO3 (C)H3PO4(d)H3PO3

Q 16.

Which of the following statements are true?
(a) Only type of interactions between particles of noble gases are due to weak dispersion forces.
(b) Ionisation enthalpy of.molecular oxygen is very close to that of xenon.
(c) Hydrolysis of XeF6 is a redox reaction.
(d) Xenon fluorides are not reactive.

Q 17.

 Why does R3P=0 exist but R3N=0 does not (R is an alkyl group) ?

Q 18.

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

Q 19.

Which aerosols deplete ozone?

Q 20.

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

Q 21.

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

Q 22.

Write two uses of ClO2

Q 23.

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

Q 24.

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 25.

 Why is N2 less reactive at room temperature?

Q 26.

Write the conditions to maximise the yield of H2SO4 by Contact process.

Q 27.

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

Q 28.

Why is N2 less reactive at room temperature?

Q 29.

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

Q 30.

Why does NH3 form hydrogen bond but PH3 does not?

Q 31.

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

Q 32.

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 33.

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 34.

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

Q 35.

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 36.

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

Q 37.

 What happens when PCl5 is heated?

Q 38.

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

Q 39.

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

Q 40.

Why is dioxygen a gas but sulphur a solid?

Q 41.

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

Q 42.

What is the covalence of nitrogen in N2O5 ?

Q 43.

Why is H2O a liquid and H2S a gas ?

Q 44.

Why does O3 act as a powerful oxidising agent?

Q 45.

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 46.

Why does nitrogen show catenation properties less than phosphorus?

Q 47.

List the uses of neoirand argon gases.

Q 48.

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
ncert-exemplar-problems-class-12-chemistry-p-block-elements-3

Q 49.

In a cyclotrimeta phosphoric acid molecule, how many single and double bonds are present? .
(a) 3 double bonds; 9 single bonds
(b) 6 double bonds; 6 single bonds
(c) 3 double bonds; 12 single bonds
(d) Zero double bonds; 12 single bonds

Q 50.

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