ISC Chemistry 2016 Class-12 Previous Year Question Paper Step by step Solutions of Part-1 and Part-2(section -A, B, C) . By the practice of ISC Chemistry 2016 Class-12 Solved Previous Year Question Paper you can get the idea of solving.

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## ISC Chemistry 2016 Class-12 Previous Year Question Paper Solved

-: Select Options :-

Part – I

Part – II Section – A

Part – II Section – B

Part – II Section – C

Maximum Marks: 70
Time allowed: 3 hours

• Answer all questions in Part I and six questions from Part II, choosing two questions from Section A, two from Section B and two from Section C.
• All working, including rough work, should be done on the same sheet as, and adjacent to, the rest of the answer.
• The intended marks for questions or parts of questions are given in brackets [ ].
• Balanced equations must be given wherever possible and diagrams where they are helpful.
• When solving numerical problems, all essential working must be shown.
• In working out problems use the following data:
Gas constant R = 1.987 cal deg-1 mol-1 = 8.314 JK-1 mol-1 = 0.0821 dm3 atm K-1 mol-1. 1 L atm = 1 dm3 atm = 101.3 J.

Part – I (20 Marks)

### ISC Chemistry 2016 Class-12 Previous Year Question Paper Solved

Question 1.
(a) Fill in the blanks by choosing the appropriate word/words from those given in the brackets: [5]
(Henry’s, aldol condensation, absence, do not, ohm, Raoult’s, increases, common ion effect, easily, three, solubility product, ohm-1, two, four, ohm-1, cm2, Cannizzaro, ohm-1 cm-1, zero, decreases, presence)
(i) Ideal solutions obey ………. law and they …………. form azeotropic mixtures.
(ii) Benzaldehyde undergoes ……….. reaction due to ………… of an α-hydrogen atom.
(iii) The solubility of silver chloride ……… in the presence of sodium chloride because of ……….
(iv) The unit of conductance is ………. and that of specific conductance is ………..
(v) When the concentration of a reactant of the first-order reaction is doubled, the rate becomes ……… times, but for ……….. order reaction, the rate remains the same.

(b) Complete the following statements by selecting the correct alternative from the choices given: [5]
(i) The electrochemical equivalent is the amount of substance which gets deposited from its solution on passing electrical charge equal to:
(1) 96,500 Coulombs
(2) 1 Coulomb
(3) 60 Coulombs
(4) 965 Coulombs

(ii) The complexion [Ni(CN)4]2- is:
(1) Square planar and diamagnetic
(2) Tetrahedral and Paramagnetic
(3) Square planar and paramagnetic
(4) Tetrahedral and Diamagnetic

(iii) Wohler’s synthesis is used for the preparation of:
(1) Glycine
(2) Amino acids
(3) Urea
(4) Proteins

(iv) When SO2 gas is passed through the acidified K2Cr2O7 solution, the colour of the solution changes to:
(1) Red
(2) Black
(3) Orange
(4) Green

(v) In the equation ,$\mathrm{CH}_{3} \mathrm{COOH}+\mathrm{Cl}_{2} \frac{\mathrm{Red} P}{-\mathrm{HCl}} \mathrm{A}$,  the compound A is:
(1) CH3CH2Cl
(2) ClCH2COOH
(3) CH3Cl
(4) CH3COCl

(c) Answer the following questions: [5]
(i) What is the order of reaction whose rate constant has the same unit as the rate of reaction?
(ii) What is the pH value of a solution whose hydroxyl ion concentration is 1 × 10-2 M?
(iii) Calculate the number of coulombs required to deposit 5.4 g of Al when the electrode reaction
is: Al3 + 3e + Al [Atomic Weight of Al 27 g/mol].
(iv) Write the reaction to prepare acetaldehyde from hydrogen gas and acid chloride.
(v) The edge length of the unit cell of a body-centred cubic (bcc) crystal is 352 pm. Calculate the radius of the atom.

(d) Match the following: [5]

 (i) Weak electrolyte (a) pH of a solution (ii) Colour in crystals (b) Iodoform (iii) Acetone (c) Tollen’s reagent (iv) Sorensen (d) Ostwald dilution law (v) Ammoniacal silver nitrate (e) F – centre

(a)

(i) Raoult’s, do not
(ii) Cannizzaro, absence
(iii) decreases, common ion effect
(iv) ohm-1, ohm-1, cm-1
(v) two, zero

(b)

(i) -1
(ii) -1
(iii) -3
(iv) -4
(v) -2

(d)

(i) (d)
(ii) (e)
(iii) (b)
(iv) (a)
(v) (c)

Part – II (50 Marks)

Answer six questions choosing two from Section A, two from Section B and two from Section C.

Section – A

### ISC Chemistry 2016 Class-12 Previous Year Question Paper Solved

Question 2.
(a)

(i) A10% aqueous solution of cane sugar (mol. wt. 342) is isotonic with 1.754% aqueous solution of urea. Find the molecular mass of urea. [2]
(ii) The molecular weight of an organic compound is 58 g mol-1. What will be the boiling point of a solution containing 48 grams of the solute in 1200 grams of water? [2]
[Kb for water = 0.513°C kg mole-1; Boiling point of water = 100°C]
(iii) What will be the value of Van’t Hoff factor (i) of benzoic acid if it dimerises in aqueous solution? How will the experimental molecular weight vary as compared to the normal molecular weight? [1]
(b)

(i) Determine thepHvalueof 0.001 M acetic acid solution if it is 2% ionised at this concentration. How can the degree of dissociation of this acetic acid solution be increased? [2]
(ii) The solubility product of PbCl2 at 298K is 1.7 × 10-5. Calculate the solubility of PbCl2 in g/lit. at 298K. [2]
Atomic Weights: [Pb = 207 and Cl = 35.5]
(c) Graphite is anisotropic with respect to the conduction of electric current. Explain. [1]
(a)

(i) 10% aqueous solution of cane sugar is isotonic with 1.754% aqueous solution of urea (MB)

(c) This is due to its chemical bonding properties. In graphite, there are C-atoms arranged in hexagonal layers which are held together by weak van der Waals forces of attraction.

Question 3.
(a)

(i) In a body centred and face centred arrangement of atoms of an element, what will be the number of atoms present in respective unit cells? Justify your answer with a calculation. [2]
(ii) A compound AB has a simple cubic structure and has molecular mass 99. Its density is 3.4 g cm-3. What will be the edge length of the unit cell? [2]
(b)

(i) For the reaction:
$\begin{array}{c}{2 \mathrm{NO}_{(\mathrm{g})} \rightleftharpoons \mathrm{N}_{2(\mathrm{g})}+\mathrm{O}_{2(\mathrm{g})} ; \Delta \mathrm{H}=-\text { heat }} \\ {\mathrm{K}_{\mathrm{e}}=2.5 \times 10^{2} \mathrm{at} 298 \mathrm{K}}\end{array}$
what will happen to the concentration of N2 if:
(1) Temperature is decreased to 273 K.
(2) The pressure is reduced
(ii) In a first-order reaction, 10% of the reactant is consumed in 25 minutes. Calculate: [2]
(1) The half-life period of the reaction.
(2) The time required for completing 87.5% of the reaction.
(c) Water acts as Bronsted acid as well as a Bronsted base. Give one example each to illustrate this statement. [2]
$${}$$