Class 12 ISC Chemistry Boards Paper 2024

(i) For a particular reaction, the value of rate constant is 0.05 sec^-1. The reaction is of _____ order and will be ____ of the initial concentration.

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(ii) EDTA is used in the treatment of _____ while Cisplatin is used in the treatment of _____

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(iii) The addition of small quantity of ethanol to chloroform prevents the formation of ______ and converts it into the harmless compound ______

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(iv) The Dehydration of ethyl alcohol with conc. H2SO₄ at 140°C mainly yields ______ while at 170°C the main product formed is ______

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(B) Select and write the correct alternative from the choices given below

(i) Which one of the following statements is correct regarding the dry cell?

(P) Zinc container acts as an anode in dry cell.
(Q) Zinc container touches the paste of MnO₂ and carbon.
(R) Dry cell can be charged easily.
(S) Graphite rod acts as a cathode in dry cell.

(a) Only (P) and (R)
(b) Only (Q) and (R)
(c) Only (P) and (S)
(d) Only (Q) and (S)

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(ii) The metal complex ion that is paramagnetic is:

(Atomic number of Fe = 26, Cu = 29, Co = 27 and Ni = 28)

(a) [Fe(CN)₄]^2-
(b) [Co(NH₃)₆]³⁺
(c) [Ni(CN)₄]^2-
(d) [Cu(NH₃)₄]²⁺

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(iii) When KMnO₄, is heated with acidified oxalic acid, gas bubbles are evolved. These gas bubbles are evolved due to the formation of:

(a) SO₂ (b) CO₂ (c) SO₃ (d) O₂

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(iv) The reaction of ethanamide with alcoholic sodium hydroxide and bromine gives:

(a) ethylamine
(b) methylamine
(c) propylamine
(d) aniline

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(v) An equimolar solution of non-volatile solutes A and B, shows a depression in freezing point in the ratio of 2:1. If A remains in its normal state in the solution, the state of B in the solution will be:

(a) normal
(b) hydrolysed
(c) associated
(d) dissociated

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(vi) Assertion: Specific conductivity of all electrolytes decreases on dilution. Reason: On dilution, the number of ions per unit volume decreases.

(a) Both Assertion and Reason are true and Reason is the cotrect explanation for Assertion
(b) Both Assertion and Reason are true but Reason is not the correct explanation for Assertion
(c) Assertion is true but Reason is false
(d) Assertion is false but Reason is true

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(vii) Assertion: Ammonolysis of alkyl halides involves the reaction between alkyl halides and alcoholic ammonia
Reason: Ammonolysis of alkyl halides produces secondary amines only.

(a) Both Assertion and Reason are true and Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct explanation for Assertion
(c) Assertion is true but Reason is false
(d) Assertion is false but Reason is true

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(C) Read the passage given below and answer the questions that follow

When two solutions are separated by a semi-permeable membrane, the solvent molecules move from a solution of lower molar concentration to a solution of higher molar concentration through osmosis.

(i) Samar removed the outer hard shell of two different eggs while cooking at home. He then placed one egg in pure water and the other egg in saturated solution of sucrose. What change is he likely to observe in the eggs after few hours?
(ii) Which solution, hypertonic or hypotonic, has a higher amount of solute in same quantity of solution?
(iii) A 5% aqueous solution of glucose (molar mass = 180 g mol^-1) is isotonic with 1.66% aqueous solution of urea. Calculate the molar mass of urea.

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(i) Write a chemical test to distinguish between ethanol and phenol.

(ii) Give a chemical reaction to convert acetaldehyde into secondary propyl alcohol.

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Give a reason for each of the following.

(i) Zinc, cadmium and mercury are considered as d-block elements but not regarded as transition elements.
(ii) Transition metals possess a great tendency to form complex compounds.

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Convert the following by giving chemical equations for each

(i) Ethyl bromide to diethyl ether
(ii) Phenol to salicylaldehyde

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Account for each of the following

(i) Zirconium (Zr) and Hafnium (Hf) are difficult to separate

(ii) Salts of Cupric (Cu²⁺) ion are coloured whereas salts of Cuprous (Cu⁺) ion are colourless.

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How will you bring the following conversions?

(i) Benzene to biphenyl
(ii) Iodoform to acetylene

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Calculate the maximum possible electrical work that can be obtained from a galvanic cell under standard conditions at 298 K.

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(i) Give a reason for each of the following

(a) Ethoxy ethane does not react with sodium, but ethanol does
(b) Ethoxy ethane with conc. HI at 373K gives C2HsOH and CHs3I but not CH₃0H and C₂H₅I.

OR

(ii) An organic compound [A] having molecular formula C₄H₁₀O forms a compound [B] with molecular formula C₄H₈O on oxidation. Compound [B] gives a positive iodoform test. The reaction of compound [B] with CH₃MgBr followed by hydrolysis gives compound [C] with molecular formula C₅H₁₂0.

Identify the compounds [A], [B] and [C]. Write the reaction for the conversion of compound [A] to compound [B].

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If 200 cm³ of an aqueous solution of a protein contains 1.26 g of protein, the osmotic pressure of the solution at 300K is found to be 2.57 x 10^-3 atm.
Calculate the molar mass of protein.

(R = 0-0821 L atm K^-1 mol^-1)

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(i) Benzaldehyde is less reactive than propionaldehyde. Why?

(ii) In the preparation of ethanal by the oxidation of ethanol, ethanal should be removed immediately as it is formed. Why?

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(i) Why is Mn⁺² ion more stable than Fe⁺² ion?
(Atomic number of Mn = 25 and Fe = 26)

(ii) Trivalent Lanthanoid ions such as La³⁺ (Z = 57) and Lu³⁺ (Z = 71) do not show any colour in their solution. Give a reason.

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For the reaction A+ B ⇌ Product, following data was obtained:



Calculate the following:

(i) The overall order of the reaction
(ii) The rate law equation
(iii) The value of rate constant

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(i) Illustrate the following reactions by giving one suitable example in each case. (a) Coupling reaction
(b) Acetylation of ethylamine

(ii) Aniline does not give Friedel-Crafts reaction. Give a reason.

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(i) Aradhana visits a physician as she is suffering from rickets and joint pain. Which fat-soluble vitamin should the physician prescribe to her?

(ii) Somesh put few drops of vinegar in milk. What change do you think he observed in the milk after some time? What is this phenomenon known as?

(iii) Name the product of hydrolysis of sucrose. Is it a reducing sugar or a non-reducing sugar?

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An aqueous solution containing 12.50 g of barium chloride in 1000g of water boils at 373.0834 K. Calculate the degree of dissociation of barium chloride. Given K_B for H₂0 = 0.52 K kg mol^-1 molecular mass of BaCl² = 208.34 g mol^-1

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An organic compound C₂H₄O gives red precipitate when heated with Fehling solution. It also undergoes aldol condensation in the presence of dilute NaOH.

(i) Identify the organic compound and write its IUPAC name
(ii) Which compound will be formed when this organic compound reacts with hydroxylamine
(iii) What is observed when the compound, referred to in subpart (i), is heated with ammonical silver nitrate?

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(i) Identify the compounds [A], [B] and [C] in each of the following reactions.



OR

(ii) Give a chemical test to distinguish between the following pairs of compounds.

(a) Ethanol and methanol
(b) Ethanol and Ethanal
(c) Propan-2-ol and 2-methyl propan-2-ol

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(i) The rate constant of a reaction at 5OOK and 700K are 0.02 sec^-1 and 0.07 sec^-1 respectively. Calculate the value of E_a (activation energy)

(ii) A radioactive substance which emits alpha particle follows first order reaction.The half-life period of this radioactive substance is 30 hours. Calculate the fraction in percent(%) of the radioactive substance which remains after 90 hours.

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(i) An organic compound [A], having a specific smell forms two compounds [B] and [C] by reacting with conc. sodium hydroxide. The molecular formula of compound [B] is C₇H₈O, which forms compound [A] again on oxidation. Compound [C] forms benzene on heating with soda lime.
Write the structures of compounds [A], [B] and [C]. Also, write the reactions involved.

(ii) Identify the compounds [A] and [B] in the reactions given below:

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(i) Acoordination compound has a formula CoCl₃.4NH₃. It precipitates silver ions as AgCl and its molar conductance corresponds to a total of two ions

Based on this information, answer the following questions

(a) Deduce structural formula of the complex compound.
(b) Write the IUPAC name of the complex compound.
(c) Draw the geometrical isomers of the complex compound.
(ii) Give a chemical test to show that [Co(NH₃)₅Cl]SO₄
[Co(NH₃)₅SO₄]Cl are ionisation isomers.

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(i) (a) Study the diagram given below that represents Cu-Ag electrochemical cell and answer the questions that follow.





(1) Write the cell reaction for the above cell.
(2) Calculate the standard emf of the cell.
(3) Ifthe concentration of [Cu²⁺] is 0.1 M and E_cell is 0.422 V, at 25°C, calculate the concentration of [Ag⁺].
(4) Calculate ▵G for the cell.

(b) Calculate ^^°_m, for BaCl₂ and Al₂(SO₄)₃ from the following data.



OR

(ii) (a) A 0.05 M NH₄OH solution offers the resistance of 30.8 ohms to a conductivity cell at 298K. If the cell constant is 0.343 cm^-1 and molar conductance of NH₄OH at infinite dilution is 471.4 S cm²mol^-1, calculate the following:

(1) Specific conductance
(2) Molar conductance
(3) Degree of dissociation

(b) Inthe diagram of the electrolytic cell given below, A, B and C are connected in series having electrolytes of ZnSO₄, AgNO₃ and CuSO₄respectively. A steady current of 1.5 A was passed until 1.45 g of Ag was deposited at the cathode of cell B.



(Atomic mass of Ag = 108, Cu = 63.5, Zn = 65.3)

Answer the following questions.

(1) How long did the current flow?
(2) What weight of Cu and Zn was deposited at cathode?

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