Chemistry

The p-Block Elements.

Question:

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

Answer:

The thermal stability of hydrides of group 16 elements decreases down the group. This is because down the group, size of the element (M) increases, M-H bond length increases and thus, stability of M-H bond decreases so that it can be broken down easily. Hence, we have order of thermal stability as H2O > H2S > H2Se > H2Te > H2PQ

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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.

Describe the manufacture of H2SO4 by contact process?

Q 9.

How does ammonia react with a solution of Cu2+?

Q 10.

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

Q 11.

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

Q 12.

How is the presence of SO2 detected ?

Q 13.

Give the resonating structures of N02 and N2O5.

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

Q 18.

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

Q 19.

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

Q 20.

Write two uses of ClO2

Q 21.

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 22.

 Why is N2 less reactive at room temperature?

Q 23.

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

Q 24.

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

Q 25.

Which aerosols deplete ozone?

Q 26.

Why is N2 less reactive at room temperature?

Q 27.

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

Q 28.

Why does NH3 form hydrogen bond but PH3 does not?

Q 29.

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

Q 30.

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

Q 31.

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 32.

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 33.

Phosphorus has three allotropic fonns —(i) white phosphorus (ii) red phosphorus and (iii) black phosphorus. Write the difference between white and red phosphorus on the basis of their structure and reactivity.

Q 34.

Assertion (A): SF6 cannot be hydrolysed but SF4 can be.
Reason (R): Six F atoms in SF6 prevent the attack of H2O on sulphur atom of SF6.

Q 35.

 What happens when PCl5 is heated?

Q 36.

Complete the following reactions:
(i)C2H2 + O2 -> (ii) 4Al + 3 O2 ->

Q 37.

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

Q 38.

 How is the presence of SO2 detected?

Q 39.

Mention three areas in which H2SO4 plays an important role.

Q 40.

Considering the parameters such as bond dissociation enthalpy, electron gain enthalpy and hydration enthalpy, compare the oxidising powers of F2 and Cl2.

Q 41.

Give two examples to show the anomalous behaviour of fluorine.

Q 42.

Name two poisonous gases which can be prepared from chlorine gas

Q 43.

Discuss the trends in chemical reactivity of group 15 elements.

Q 44.

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

Q 45.

How is ammonia manufactured industrially?

Q 46.

Give the disproportionation reaction of H3 P03.

Q 47.

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

Q 48.

Why is dioxygen a gas but sulphur a solid?

Q 49.

 Describe the manufacture of H2SO4 by contact process?

Q 50.

 Why are halogens strong oxidising agents?