Chemistry

The p-Block Elements.

Question:

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

Answer:

The three oxyacids of nitrogen are:
ncert-exemplar-problems-class-12-chemistry-p-block-elements-37

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The p-Block Elements.

Q 1.

 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 2.

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

Q 3.

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 4.

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

Q 5.

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

Q 6.

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

Q 7.

In the ring test of NO3 ion.Fe2+ion reduces nitrate ion to nitric oxide, which combines with Fe2+  (aq.) ion to form brown complex. Write the reactions involved in the formation of brown ring.

Q 8.

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

Q 9.

 Write two uses of ClO2

Q 10.

Discuss the trends in chemical reactivity of group 15 elements.

Q 11.

Give the resonating structures of N02 and N2O5.

Q 12.

Why are halogens strong oxidising agents?

Q 13.

Write the reactions of F2 and Cl2 with water.

Q 14.

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

Q 15.

Give the reason for bleaching action of Cl2.

Q 16.

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

Q 17.

 With which neutral molecule is ClO isoelectronic? Is this molecule Lewis acid or base ? (Pb. Board 2009)

Q 18.

 How are XeOand XeOF4prepared?

Q 19.

 Why do noble gases have comparatively large atomic size?

Q 20.

Why is N2 less reactive at room temperature?

Q 21.

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

Q 22.

List the important sources of sulphur.

Q 23.

Why does O3 act as a powerful oxidising agent?

Q 24.

How is O3 estimated quantitatively?

Q 25.

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

Q 26.

Write two uses of ClO2

Q 27.

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

Q 28.

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 29.

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

Q 30.

How does ammonia react with a solution of Cu2+?

Q 31.

 What happens when PCl5 is heated?

Q 32.

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

Q 33.

 Why are halogens strong oxidising agents?

Q 34.

Write the reactions of F2 and Cl2 with water.

Q 35.

Why are pentahalides more covalent than trihalidcs ?

Q 36.

How does ammonia react with a solution of Cu2+?

Q 37.

How is the presence of SO2 detected ?

Q 38.

Nitrogen exists as diatomic molecule and phosphorus as P4. Why?

Q 39.

Why does nitrogen show catenation properties less than phosphorus?

Q 40.

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

Q 41.

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 42.

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 43.

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 44.

 What is the covalence of nitrogen in N2O5 ?

Q 45.

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

Q 46.

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

Q 47.

 What happens when H3PO4 is heated?

Q 48.

 Which of the following does not react with oxygen directly? Zn, Ti, Pt, Fe

Q 49.

Why does O3 act as a powerful oxidising agent?

Q 50.

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