Chemistry

The p-Block Elements.

Question:

Why is ICI more reactive than l2?

Answer:

In general, interhalogen compounds are more reactive than halogens due to weaker X-X’ bonding than X-X bond. Thus, ICI is more reactive than I2.

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The p-Block Elements.

Q 1.

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

Q 2.

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 3.

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

Q 4.

Justify the placement of O, S, Se, Te and Po in the same group’of the periodic table in terms of electronic configuration, oxidation state and hydride formation.

Q 5.

Why is dioxygen a gas but sulphur a solid?

Q 6.

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

Q 7.

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

Q 8.

Why is dioxygen a gas but sulphur a solid?

Q 9.

How is O3 estimated quantitatively?

Q 10.

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

Q 11.

Discuss the trends in chemical reactivity of group 15 elements.

Q 12.

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.

Q 13.

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 14.

Why does O3 act as a powerful oxidising agent?

Q 15.

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 16.

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

Q 17.

Give the disproportionation reaction of H3 P03.

Q 18.

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

Q 19.

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

Q 20.

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

Q 21.

Why does nitrogen show catenation properties less than phosphorus?

Q 22.

On heating with concentrated NaOH solution in an inert atmosphere of CO2, white phosphorus gives a gas. Which of the following statement is incorrect about the gas?
(a) It is highly poisonous and has smell like rotten fish.
(b) Its solution in water decomposes in the presence of light.
(c) It is more basic than NH3  
(d) It is less basic than NH3

Q 23.

Which of the following orders are correct as per the properties mentioned against each?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-23

Q 24.

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 25.

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 26.

What is the basicity of H3PO4?

Q 27.

Why is ICI more reactive than l2?

Q 28.

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

Q 29.

Give the resonating structures of N02 and N2O5.

Q 30.

 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 31.

 Why are halogens strong oxidising agents?

Q 32.

Explain why fluorine forms only one oxoacid, HOF.

Q 33.

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

Q 34.

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

Q 35.

How are xenon fluorides XeF2, XeF4 and XeFobtained?

Q 36.

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

Q 37.

 Arrange the following in the order of property indicated for each set: –
(i) F2 , Cl2 , Br2 , I2 – increasing bond dissociation enthalpy.
(ii) HF, HCI, HBr, HI – increasing acid . strength.
(iii) NH3, PH3, AsH3, SbH3, BiH3 – increasing Sol. base strength.

Q 38.

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

Q 39.

What is the basicity of H3PO4?

Q 40.

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

Q 41.

Discuss the general characteristics of Group 15 elements with reference to their electronic configuration, oxidation state, atomic size, ionisation enthalpy and electronegativity.

Q 42.

Why does NH3 form hydrogen bond but PH3 does not?

Q 43.

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

Q 44.

Justify the placement of O, S, Se, Te and Po in the same group'of the periodic table in terms of electronic configuration, oxidation state and hydride formation.

Q 45.

How is SO2 an air pollutant?

Q 46.

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

Q 47.

Why are halogens coloured?

Q 48.

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 49.

How are XeO3  and XeOF4prepared?

Q 50.

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