Chemistry

The p-Block Elements.

Question:

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.

Answer:

(a, c, d) Among halogens radius ratio between iodine and fluorine is maximum because iodine has maximum radius while fluorine has minimum radius. Also, due to highest radius ratio maximum number of atoms are present in iodine fluoride.
Interhalogen compounds are more reactive than halogen compounds because A – B bond of dissimilar halogen is weaker than A – A or B – B bond of halogens.

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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.

How is O3 estimated quantitatively?

Q 9.

Why is dioxygen a gas but sulphur a solid?

Q 10.

Why does O3 act as a powerful oxidising agent?

Q 11.

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

Q 12.

Discuss the trends in chemical reactivity of group 15 elements.

Q 13.

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 14.

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 15.

Why is ICI more reactive than l2?

Q 16.

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

Q 17.

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

Q 18.

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 19.

Give the disproportionation reaction of H3 P03.

Q 20.

 Why are halogens strong oxidising agents?

Q 21.

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

Q 22.

Why does nitrogen show catenation properties less than phosphorus?

Q 23.

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 24.

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 25.

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 26.

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 27.

What is the basicity of H3PO4?

Q 28.

Why is H2O a liquid and H2S a gas?

Q 29.

Explain why NH3 is basic while BiH3 is only feebly basic.

Q 30.

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

Q 31.

 How is SO2 an air pollutant?

Q 32.

Explain why fluorine forms only one oxoacid, HOF.

Q 33.

How are xenon fluorides XeF2, XeF4 and XeFobtained?

Q 34.

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

Q 35.

Why are pentahalides more covalent than trihalidcs ?

Q 36.

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

Q 37.

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

Q 38.

Why does NH3 form hydrogen bond but PH3 does not?

Q 39.

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 40.

Why are halogens coloured?

Q 41.

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 42.

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 43.

Which of the following pairs of ions are isoelectronic and isostructural?
ncert-exemplar-problems-class-12-chemistry-p-block-elements-6

Q 44.

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 45.

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 46.

On reaction with Cl2, phosphorus forms two types of halides ‘A' and ‘B'. Halide A is yellowish-white powder but halide B' is colourless oily liquid. Identify A and B and write the formulas of their hydrolysis products.

Q 47.

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 48.

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

Q 49.

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

Q 50.

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