ISC Chemistry 2019 Class-12 Previous Year Question Paper Step by step Solutions . By the practice of ISC Chemistry 2019 Class-12 Solved Previous Year Question Paper you can get the idea of solving. Try Also other year except ISC Chemistry  2019 Class-12 Solved Question Paper of Previous Year for more practice. Because only ISC Chemistry 2019 Class-12 is not enough for complete preparation of next council exam. Visit official website CISCE for detail information about about ISC Class-12 Physics.

## ISC Chemistry 2019 Class-12 Previous Year Question Paper Solved

Maximum Marks: 70

Time allowed: 3 hours

• Candidates are allowed additional 15 minutes for only reading the paper.
• They must not start writing during this time.
• All questions are compulsory.
• Question 1 is of 20 marks having four subparts, all of which are compulsory.
• Question numbers 2 to 8 carry 2 marks each, with two questions having internal choice.
• Question numbers 9 to 15 carry 3 marks each, with two questions having an internal choice.
• Question numbers 16 to 18 carry 5 marks each, with an internal choice.
• 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
• 11 atm = 1 dm3 atm = 101.3 J. 1 Faraday = 96500 coulombs.
• Avogadro’s number = 6.023 × 1023.

### ISC Chemistry 2019 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: [4 × 1]
(more than, primary, cathode, Lucas reagent, two, four, less than, Grignard’s reagent, tertiary, anode, zero, equal to, three)
(i) The elevation of a boiling point of 0.5 M K2SO4 solution is ……….. that of 0.5 M urea solution. The elevation of the boiling point of 0.5 M KCl solution is …………. that of 0.5 M K2SOsolution.
(ii) A mixture of conc. HCl and anhydrous ZnCl2 is called ……….. which shows maximum reactivity with ……….. alcohol.
(iii) In electrolytic refining, the impure metal is made ………. while a thin sheet of pure metal is used as ………..
(iv) When the concentration of a reactant of the first-order reaction is doubled, the rate of reaction becomes ………… times, but for a ……… order reaction, the rate of reaction remains the same.

(b) Select the correct alternative from the choices given: [4 × 1]
(i) The cell reaction is spontaneous or feasible when emf of the cell is:
(1) negative
(2) positive
(3) zero
(4) either positive or negative

(ii) Which, among the following polymers, is a polyester:
(1) melamine
(2) bakelite
(3) terylene
(4) polythene

(iii) The correct order of increasing acidic strength of the oxoacids of chlorine is:
(1) HCIO3 < HClO4 < HClO2 < HClO
(2) HClO < HClO2 < HClO3 < HClO4
(3) HClO2 < HClO < HClO4 < HClO3
(4) HClO3 < HClO4 < HClO < HClO2

(iv) A catalyst is a substance which:
(1) changes the equilibrium constant of the reaction
(2) increases the equilibrium constant of the reaction
(3) supplies energy to the reaction
(4) shortens the time to reach equilibrium.

(c) Match the following: [4 × 1]

 (i) Diazotisation (a) Anisotropic (ii) Crystalline solid (b) Reimer-Tiemann reaction (iii) Phenol (c) Diphenyl (iv) Fitting reaction (d) Aniline

(d) Answer the following questions: [4 × 2]
(i)

(1) Which trivalent ion has a maximum size in the Lanthanoid series i.e., Lanthanum ion (La3+) to Lutetium ion (Lu3+)?
(at. no. of Lanthanum = 57 and Lutetium = 71)
(2) Explain why Cu2+ is paramagnetic but Cu+ is diamagnetic.
(at. no. of Cu = 29)
(ii) When a coordination compound C0Cl3.6NH3 is mixed with AgNO3, three moles of AgCl are precipitated per mole of the compound. Write the structural formula and IUPAC name of the coordination compound.
(iii) Calculate the boiling point of urea solution when 6 g of urea is dissolved in 200 g of water. (Kb for water = 0.52 K kg mol-1, boiling point of pine water = 3 73 K, mol. wt. of urea = 60)
(iv) Identify the compounds A, B, C and D in the given reaction:

(a)

(i) more than, less than
(ii) Lucas reagent, tertiary
(iii) anode, cathode
(iv) two, zero

(b) (i) → (2)
(ii) → (3)
(iii) → (2)
(iv) → (4)

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

Cu2+ has one unpaired electron. Therefore, it is paramagnetic. Cu+ has no unpaired electrons. Therefore, it is diamagnetic.
(ii) [CO(NH3)6]Cl3
hexamine cobalt (III) chloride

(iv) A – CH3CHO, Acetaldehyde
B – CH3COOH, Acetic acid
C – (CH3COO)2Ca, Calcium acetate
D – CH3COCH3, Acetone

#### Question 2. [2]

(a) For the reaction A + B → C + D, the initial rate for different reactions and initial concentration of reactants are given below:

(i) What is the overall order of reaction?
(ii) Write the rate law equation.
or
(b) 25% of a first-order reaction is completed in 30 minutes. Calculate the time taken in minutes for the reaction to go to 90% completion.

#### Question 3. [2]

1. Name the type of drug which lowers the body temperature in high fever condition.
2. What are tranquilizers? Give one example of tranquilizer.

1. Antipyretics
2. Tranquilizers: These are the drugs which are used for the treatment of stress, fatigue, mild and severe mental diseases.
For example phenelzine

#### Question 4. [2]

Write the balanced chemical equation for each of the following:
(i) Chlorobenzene treated with ammonia in the presence of Cu2O at 475 K and 60 atm.
(ii) Ethyl chloride treated with alcoholic potassium hydroxide.

#### Question 5. [2]

1. Name the monomer and the type of polymerisation that takes place when PTFE is formed.
2. Name the monomers of nylon 6, 6.

1. Tetrafluoroethylene, F2C = CF2
2. Monomers of nylon – 6, 6 are hexamethylene diamine and adipic acid

Question 6. [2]
Name two water-soluble vitamins and the diseases caused by their deficiency in the diet of an individual.
Two water-soluble vitamins are

• Vitamin C, Deficiency disease – Haemorrhage
• Vitamin B1 – Deficiency disease – Beriberi

Question 7. [2]
(a) How will you obtain the following? (Give balanced chemical equations):
(i) Benzene from phenol.
(ii) Iodoform from ethanol.
Or
(b) How will you obtain the following? (Give balanced chemical equations):
(i) Salicylaldehyde from phenol.
(ii) Propan-2-ol from Grignard’s reagent.

Question 8.
Show that for a first-order reaction the time required to complete 75% of reaction is about 2 times more than that required to complete 50% of the reaction.
For a first-order reaction
$t=\frac{2 \cdot 303}{k} \log \frac{a}{a-x}$

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