Goa Board Class 12 Question Paper June 2018 Chemistry _New Pattern_

2018 VI 11 1430 Seat No. :

Time : 2½ Hours CHEMISTRY (New Pattern)

Subject Code

H 7 0 3

Total No. of Questions : 27 (Printed Pages : 4) Maximum Marks : 55

INSTRUCTIONS : 1) All questions are compulsory, however question numbers
14, 21, 26 and 27 have internal choice.
2) Section – A consists of 9 questions of 1 mark each.
Section – B consists of 10 questions of 2 marks each.
Section – C consists of 6 questions of 3 marks each.
Section – D consists of 2 questions of 4 marks each.
3) Every question should be attempted only once.
4) Use of calculator is not permitted, however logarithmic
table will be provided on request.
SECTION – A
1. The Van’t Hoff factor ‘i’ for a solution of acetic acid in benzene will be ________ [1]
• greater than one • less than one
• equal to one • zero
2. The bond that stabilises the secondary structure of protein is _________ [1]
• covalent bond • coordinate bond
• ionic bond • hydrogen bond
3. When 2-chlorobutane reacts with hot alcoholic KOH, the major product formed
is _________ [1]
• But – 1 – ene • Butan – 1 – ol
• But – 2 – ene • Butan – 2 – ol
4. Among the following oxides of manganese, the acidic oxide is ________ [1]
• MnO • Mn3O4
• Mn2O3 • Mn2O7
5. The monomeric units of the given polymer
are ___________ [1]
• glycine and formaldehyde • urea and formaldehyde
• urea and ethanol • glycine and adipic acid

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6. Write any two characteristics of molecular solids. [1]
7. Arrange the following alcohols in the decreasing order of their boiling points : [1]
Pentan – 1 – ol, 2 – Methylbutan – 2 – ol,
3 – Methylbutan – 2 – ol
8. Write chemical equation for the preparation of Buna – N. [1]
9. Give reason why aromatic carboxylic acids do not undergo Friedel – Crafts
reaction. [1]
SECTION – B
10. Draw neat labelled diagram of the stoichiometric defect observed in ionic solids
having ions of similar size. What is the effect of this defect on the density of the
crystal ? [2]
11. Derive the integrated rate equation for a first order reaction. [2]
12. Calculate the activation energy of a reaction whose rate constants are 1.2 × 10–3 s–1
and 2.4 × 10–3 s–1 at 30°C and 40°C respectively. [R = 8.314 JK–1 mol–1] [2]
13. a) Draw a neat labelled diagram of hydrogen – oxygen fuel cell.
b) Predict the products of electrolysis of dilute sulphuric acid at the respective
electrodes. [2]

14. Calculate the emf at 25°C of an electrochemical cell in which the following
reaction occurs :
Mg (s)
Cu (aq)  Mg (aq)
Cu (s) and the concentration of Mg2+ ions




is 100 times more than Cu2+ ions.
Given E



C u



/ C u

0.34 V , EM



g



/ M g

2.37 V [2]
OR
Calculate the equilibrium constant for the following cell at 25°C :
Ni Ni (aq) Ag (aq) Ag




Given E 
0.25 V , E
0.80 V








N i N i ) C ) C

15. Complete the following equations and write the name of the major products ‘A’
and ‘B’
a) CH3 – CH2 – CH = CH2 + HBr

 A

b) dry ether
+ Na





 B [2]

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16. Name the following :
a) The vitamin responsible for blood coagulation.
b) The linkage that holds the nucleotides together in nucleic acids.
c) The dipolar ion formed by aminoacids in aqueous solution.
d) Water insoluble component on starch. [2]
17. An organic compound ‘A’ with molecular formula C7H8O reacts with HI and
forms compound ‘B’. Compound ‘B’ on heating with zinc dust gets converted to
the simplest aromatic hydrocarbon. Write equations for the above reactions and
name the compounds ‘A’ and ‘B’. [2]
18. a) Give two examples of broad spectrum antibiotics.
b) What type of detergents are used for dish washing ? [2]
19. Complete the following reactions :
a) XeF4 + O2F2

 b) Ca(OH)2 + Cl2

 [2]
SECTION – C
20. Draw a graph depicting the deviation from Raoult’s law exhibited by a solution
prepared by mixing ethanol and acetone.
Calculate the molar mass of a non volatile solute 1.8 grams of which have been
dissolved in 25 grams of acetone and the solution boils at 56.86°C. Pure acetone
boils at 56.38°C. The molal elevation constant for acetone is 1.72 k kg mol–1. [3]
21. Draw a neat labelled diagram of the electrophoresis of gold sol. Define sorption.
Give two points of distinction between lyophilic and lyophobic colloids with respect
to stability and reversibility. [3]
OR
Draw a neat labelled diagram to show the preparation of colloids by Bredig arc
method. What is peptization ? Give two points of distinction between physisorption
and chemisorption with respect to specificity and nature of forces between
adsorbate and adsorbent.
22. Write chemical equations for the conversion of each of the following :
a) Acetamide to methylamine.
b) Benzene diazonium chloride to phenol.
c) Aniline to sulphanilic acid. [3]
23. Give reasons for the following :
a) There is a steady decrease in atomic or ionic radii of lanthanoids from
Lanthanum to Lutetium.
b) Transition elements exhibit catalytic properties.
c) Paramagnetic character in the first transition series increases upto manganese
and then decreases. [3]
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24. Draw the structures of optical isomers of [Pt Cl2 (en)2]2+. Using Valence Bond
Theory, deduce the hybridization scheme of the outer orbital complex [Co F6]3–.
Comment on its magnetic behaviour. [3]

25. Draw a neat labelled diagram of Froath floatation process used for the concentration
of sulphide ores. State the principle behind (a) zone refining (b) chromatographic
methods, used for refining elements. [3]

SECTION – D

26. Answer the following :
a) Draw the structure of PCl5.
b) Write any two reasons for anomalous behaviour of nitrogen.
c) Name the allotrope of phosphorous that exhibits chemiluminescence.
d) Arrange the hydrides of group 15 elements in the decreasing order of their
basicity. [4]
OR
Answer the following :
a) Draw the structure of H2SO3.
b) Write any 2 anomalous properties of oxygen.
c) Name the allotrope of sulphur that is stable at room temperature.
d) Arrange the dioxides of group 16 elements in the decreasing order of their
reducing property.

27. Write labelled chemical equations to show what happens when :
a) Sodium propionate is heated with sodalime.
b) Acetone reacts with sodiumhypoiodite.
c) Benzaldehyde reacts with a nitrating mixture.
d) Ethanenitrile reacts with stannous chloride and HCl followed by hydrolysis. [4]
OR
Write labelled chemical equations to show what happens when :
a) Toluene reacts with chlorine in the presence of light followed by hydrolysis
at 373 K.
b) Acetophenone reacts with zinc amalgam and hydrochloric acid.
c) Formaldehyde reacts with phenylmagnesium bromide followed by hydrolysis.
d) Vapours of Butan-2-ol are passed over heated copper at 573 K.
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