Board Paper of Class 12-Science 2016 Chemistry All India(SET 2) - Solutions

For a reaction : ${\mathrm{H}}_2 + {\mathrm{Cl}}_2\stackrel{ \mathrm{hv} }{\to }2 \mathrm{HCl}$

Rate = k

(i) Write the order and molecularity of this reaction.
(ii) Write the unit of k.

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Write the chemical equations involved in the following reactions:

(i) Hoffmann-bromamide degradation reaction
(ii) Carbylamine reaction

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(i) Gas (A) is more soluble in water than Gas (B) at the same temperature. Which one of the two gases will have the higher value of K_H (Henry's constant) and why?

(ii) In non-ideal solution, what type of deviation shows the formation of maximum boiling azeotropes? VIEW SOLUTION

When a coordination compound CoCl₃.6NH₃ is mixed with AgNO₃, 3 moles of AgCl are precipitated per mole of the compound. Write

(i) Structural formula of the complex

(ii) IUPAC name of the complex

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Write the structures of the following:

(i) BrF₃
(ii) XeF₄
                                          OR

What happens when:

(i) SO₂ gas is passed through an aqueous solution Fe³⁺ salt?
(ii) XeF₄ reacts with SbF₅?

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Write the final product(s) in each of the following reactions:

(a)


(b)



(c)

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How do you convert:
(i) Chlorobenzene to biphenyl
(ii) Propene to 1-iodopropane
(iii) 2-bromobutane to but-2-ene

Write the major products(s) in the following:

(i)

(ii)

(iii)

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(i) Write the structural difference between starch and cellulose.

(ii) What type of linkage is present in Nucleic acids?

(iii) Give one example each for fibrous protein and globular protein. VIEW SOLUTION

(i) Name the method of refining of nickel
(ii) What is the role of cryolite in the extraction of aluminium?
(iii) What is the role of limestone in the extraction of iron from its oxides? VIEW SOLUTION

Give reasons:

(i) SO₂ is reducing while TeO₂ is an oxidizing agent.

(ii) Nitrogen does not form pentahalide.

(iii) ICl is more reactive than I₂. VIEW SOLUTION

(a) For the complex [Fe(H₂O)₆]³⁺, write the hybridization, magnetic character and spin of the complex. (At, number: Fe = 26)

(b) Draw one of the geometrical isomers of the complex [Pt(en)₂Cl₂]²⁺ which is optically inactive. VIEW SOLUTION

An element crystallizes in a b.c.c. lattice with cell edge of 500pm. The density of the element is 7.5g cm^–3. How many atoms are present in 300 g of the element? VIEW SOLUTION

(i) What is the role of Sulphur in the vulcanization of rubber?

(ii) Identify the monomers in the following polymer :



(iii) Arrange the following polymers in the increasing order of their intermolecular forces:
Terylene, Polythene, Neoprene VIEW SOLUTION

For the first order thermal decomposition reaction, the following data were obtained:

C₂H₅Cl(g) → C₂H₄(g) + HCl(g)

Time/sec	Total pressure/ atm
0	0.30
300	0.50

Calculate the rate constant.
(Given: log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021) VIEW SOLUTION

Give reasons for the following:

(i) Aniline does not undergo Friedal-Crafts reaction.

(ii) (CH₃)₂NH is more basic than (CH₃)₃N in an aqueous solution.

(iii) Primary amines have higher boiling point than tertiary amines. VIEW SOLUTION

Define the following terms:

(i) Lyophilic colloid
(ii) Zeta potential
(iii) Associated colloids

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Calculate the boiling point of solution when 4 g of MgSO₄ (M = 120 g mol^–1) was dissolved in 100 g of water, assuming MgSO₄ undergoes complete ionization.

(K_b for water = 0.52 K kg mol^–1) VIEW SOLUTION

Due to hectic and busy schedule, Mr. Singh started taking junk food in the lunch break and slowly became habitual of eating food irregularly to excel in his field. One during meeting he felt severe chest pain and fell down. Mr. Khanna a close friend of Mr. Singh took him to doctor immediately. The doctor diagnosed that Mr. Singhwas suffering from acidity and prescribed some medicines. Mr. Khanna advised hime to eat home made food and change his lifestyle by doing yoga, meditation and some physical exercise. Mr. Singh followed his friend's advice and after few days he started feeling better.

After reading the above passage, answer the following:
(i) What are the values (at least two) displayed by Mr. Khanna?
(ii) What are antacids? Give one example.
(iii) Would it be advisable to take antacids for a long period of time? Give reason.

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 (a) Write the structures of A and B in the following reactions:

      (i)
      (ii)

(b) Distinguish between:
     (i) C₆H₅ – COCH₃ and C₆H₅ – CHO
     (ii) CH₃COOH and HCOOH

(c) Arrange the following in the increasing order of their boiling points:
     CH₃CHO, CH₃COOH, CH₃CH₂OH   
                             
                                            OR

(a) Write the chemical reaction involved in Wolff-Kishner reduction.

(b) Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction:

     C₆H₅COCH₃, CH₃ – CHO, CH₃COCH₃

(c) Why carboxylic acid does not give reactions of carbonyl group?

(d) Write the product in the following reaction

     ${\mathrm{CH}}_3 {\mathrm{CH}}_2 \mathrm{CH}=\mathrm{CH}-{\mathrm{CH}}_2\mathrm{CN} \underset{2. {\mathrm{H}}_2\mathrm{O} }{\overset{1. {\left(\mathrm{i}-\mathrm{Bu}\right)}_2 \mathrm{AlH}}{\to }}$
 
(e) A and B are two functional isomers of compound C₃H₆O. On heating with NaOH and I₂, isomer B forms yellow precipitate of iodoform, whereas isomer A does not form any precipitate. Write the formulae of A and B. VIEW SOLUTION

(a) Calculate E°_cell for the following reaction at 298 K: (b) Using the E° values of A and B, predict which is better for coating the surface of iron [E°(Fe²⁺/Fe) = –0.44V] to prevent corrosion and why?  
(a) The conductivity of 0.001 mol L^–1 solution of CH₃COOH is 3.905 × 10^–5 S cm^–1. Calculate its molar conductivity and degree of dissociation (α).
Given λ⁰ (H⁺) = 349.6 S cm² mol^–1 and λ⁰ (CH₃COO^–) = 40.9 S cm² mol^–1

(b) Define electrochemical cell. What happens if external potential applied becomes greater than  E°_cell of electrochemical cell? VIEW SOLUTION

(a) Account for the following:

(i) Mn shows the highest oxidation state of +7 with oxygen but with fluorine, it shows the highest oxidation state of + 4.

(ii) Cr²⁺ is a strong reducing agent.
(iii) Cu²⁺ salts are coloured, while Zn²⁺ salts are white.

(b) Complete the following equations:

(i) $2{\mathrm{MnO}}_2+4\mathrm{KOH}+{\mathrm{O}}_2\stackrel{ ∆ }{\to }$
(ii) ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+14{\mathrm{H}}^{+}+6{\mathrm{I}}^{-}\stackrel{ }{\to }$
The elements of 3d transition series are given as:

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Answer the following:

(i) Write the element which shows maximum number of oxidation states. Give reason.
(ii) Which element has the highest m.p?
(iii) Which element shows only + 3 oxidation state?
(iv) Which element is a strong oxidizing agent in + 3 oxidation state and why? VIEW SOLUTION