केन्द्रीय विद्यालय संगठन कोलकाता संभाग
KENDRIYA VIDYALAYA SANGATHAN KOLKATA REGION
1st प्री बोर्ड परीक्षा / 1st PRE-BOARD EXAMINATION – 2024-25
कक्षा / CLASS: बारहवीं / XII अधिकतम अंक / Maximum marks = 70
धवषय / SUB: रसायन धवज्ञान / CHEMISTRY समय / Time: 3 घंटे / 3 hours
General Instructions:
Read the following instructions carefully and follow them :
(i) This question paper contains 33 questions. All questions are compulsory.
(ii) This question paper is divided into five sections Section A, B, C, D and E.
(iii) Section A questions number 1 to 16 are multiple choice type questions. Each question carries 1 mark.
(iv) Section B questions number 17 to 21 are very short answer type questions each carrying 2 marks .
(v) Section C questions number 22 to 28 are short answer type questions. Each question carries 3 marks.
(vi) Section D questions number 29 and 30 are case-based questions. Each question carries 4 marks.
(vii) Section E questions number 31 to 33 are long answer type questions. Each question carries 5 marks.
(viii) There is no overall choice given in the question paper. However, an internal choice has been
provided in few questions in all the sections except Section A.
(ix) Use of log tables & calculators are not allowed.
SECTION A
1. On addition of small amount of KMnO4 to concentrated H2SO4, a green oily compound is obtained
which is highly explosive in nature. Identify the compound from the following: -
(a) Mn2O7 (b) MnO2 (c) MnSO4 (d) Mn2O3.
2. Among the following alkenes which one produces tertiary butyl alcohol on acid hydration?
(a) CH3 – CH = CH2 (b) CH3 – CH = CH – CH3 (c) CH3 – CH2 – CH = CH2 (d) (CH3)2C = CH2
3. K2Cr2O7 is preferred to Na2Cr2O7 for the use in volumetric analysis as a primary standard solution
because
(a) Na2Cr2O7 is hygroscopic while K2Cr2O7 is not. (b) K2Cr2O7 is hygroscopic but Na2Cr2O7 is not.
(c) K2Cr2O7 is pure while Na2Cr2O7 is impure. (d) Na2Cr2O7 is unstable & does not form.
4. Which of the following statements is not true about glucose?
(a) It is an aldohexose. (b) On heating with HI, it forms n-hexane.
(c) It is present in cyclic furanose form. (d) It does not give 2,4- DNP test.
5. Molecule whose mirror image is non-superimposable over them are known as chiral. Which of the
following molecules is chiral in nature?
(a) 1 – bromo – 3 – methyl butane (b) 2 – bromobutane
(c) 3 – Bromo pentane. (d) 2 – bromo propan – 2 – ol.
6. Which of the following reagent cannot be used to oxidise primary alcohols to aldehydes?
(a) CrO3 in anhydrous medium. (b) Pyridinium chloro chromate
(c) KMnO4 in acidic medium. (d) Heat in presence of Cu at 573 K.
7. Hoffmann bromide degradation reaction is shown by ………...in presence of…………….
(a) Ar-NH2, CHCl3 / alc.KOH (b) Ar-CONH2, Br2 / alc. NaOH
(c) Ar-NO2, Br2 / alc. NaOH (d) Ar-CONH, CHCl3 / alc. NaOH.
Page 1 of 6
, 8. An endothermic reaction with high activation energy for
the forward reaction is given by which diagram shown in
the graph?
9. Which among the following is a false statement?
(a) Rate of a zero-order reaction is independent of initial concentration of reactant.
(b) Half-life of zero order reaction is inversely proportional to initial concentration of the reactant.
(c) Molecularity of a reaction may be zero or fraction.
(d) For a first order reaction, half-life is independent of initial concentration of reactants.
10. The geometry and magnetic behaviour of the complex [Ni(CO)4] are (at. no. of Ni = 28)
(a) Square planar and paramagnetic. (b) Tetrahedral and diamagnetic
(c) Square planar and diamagnetic. (d) Tetrahedral and paramagnetic.
11. Compounds A and C in the following reaction are ……………...?
(𝐢) 𝐂𝐇𝟑 𝐌𝐠𝐁𝐫 (𝐢𝐢)𝐇𝟐 𝐎 𝐇𝟐 𝐒𝐎𝟒, ∆ (𝐢)𝐁𝟐 𝐇𝟔 (𝐢𝐢) 𝐇𝟐 𝐎𝟐 ,𝐎𝐇−
CH3CHO→ (A) → (B) → (C)
(a) identical (b) positional isomers (c) functional isomers (d) optical isomers.
12. Which of the following cannot be prepared by Sandmeyer’s reaction?
(a) Benzonitrile (b) chlorobenzene (c) bromobenzene (d) iodobenzene.
13. Assertion (A): In K4*Fe(CN)6+, Fe2+ shows diamagnetic behavior according to crystal field theory.
Reason (R): Due to the presence of strong ligand field, ∆o < P, unpaired electrons pair up.
Select the most appropriate answer from the options given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
14. Assertion (A): The cell potential of mercury cell is 1.35 V which remains constant throughout its life.
Reason (R): In mercury cell, the electrolyte is a paste of KOH & ZnO.
Select the most appropriate answer from the options given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
15. Assertion (A): Hydrolysis of ethyl acetate in presence of dilute acid is a reaction of first order
whereas in presence of alkali solution, it is a reaction of second order.
Reason (R): Acid only acts as a catalyst whereas alkali acts as one of the reactants.
Select the most appropriate answer from the options given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Page 2 of 6
KENDRIYA VIDYALAYA SANGATHAN KOLKATA REGION
1st प्री बोर्ड परीक्षा / 1st PRE-BOARD EXAMINATION – 2024-25
कक्षा / CLASS: बारहवीं / XII अधिकतम अंक / Maximum marks = 70
धवषय / SUB: रसायन धवज्ञान / CHEMISTRY समय / Time: 3 घंटे / 3 hours
General Instructions:
Read the following instructions carefully and follow them :
(i) This question paper contains 33 questions. All questions are compulsory.
(ii) This question paper is divided into five sections Section A, B, C, D and E.
(iii) Section A questions number 1 to 16 are multiple choice type questions. Each question carries 1 mark.
(iv) Section B questions number 17 to 21 are very short answer type questions each carrying 2 marks .
(v) Section C questions number 22 to 28 are short answer type questions. Each question carries 3 marks.
(vi) Section D questions number 29 and 30 are case-based questions. Each question carries 4 marks.
(vii) Section E questions number 31 to 33 are long answer type questions. Each question carries 5 marks.
(viii) There is no overall choice given in the question paper. However, an internal choice has been
provided in few questions in all the sections except Section A.
(ix) Use of log tables & calculators are not allowed.
SECTION A
1. On addition of small amount of KMnO4 to concentrated H2SO4, a green oily compound is obtained
which is highly explosive in nature. Identify the compound from the following: -
(a) Mn2O7 (b) MnO2 (c) MnSO4 (d) Mn2O3.
2. Among the following alkenes which one produces tertiary butyl alcohol on acid hydration?
(a) CH3 – CH = CH2 (b) CH3 – CH = CH – CH3 (c) CH3 – CH2 – CH = CH2 (d) (CH3)2C = CH2
3. K2Cr2O7 is preferred to Na2Cr2O7 for the use in volumetric analysis as a primary standard solution
because
(a) Na2Cr2O7 is hygroscopic while K2Cr2O7 is not. (b) K2Cr2O7 is hygroscopic but Na2Cr2O7 is not.
(c) K2Cr2O7 is pure while Na2Cr2O7 is impure. (d) Na2Cr2O7 is unstable & does not form.
4. Which of the following statements is not true about glucose?
(a) It is an aldohexose. (b) On heating with HI, it forms n-hexane.
(c) It is present in cyclic furanose form. (d) It does not give 2,4- DNP test.
5. Molecule whose mirror image is non-superimposable over them are known as chiral. Which of the
following molecules is chiral in nature?
(a) 1 – bromo – 3 – methyl butane (b) 2 – bromobutane
(c) 3 – Bromo pentane. (d) 2 – bromo propan – 2 – ol.
6. Which of the following reagent cannot be used to oxidise primary alcohols to aldehydes?
(a) CrO3 in anhydrous medium. (b) Pyridinium chloro chromate
(c) KMnO4 in acidic medium. (d) Heat in presence of Cu at 573 K.
7. Hoffmann bromide degradation reaction is shown by ………...in presence of…………….
(a) Ar-NH2, CHCl3 / alc.KOH (b) Ar-CONH2, Br2 / alc. NaOH
(c) Ar-NO2, Br2 / alc. NaOH (d) Ar-CONH, CHCl3 / alc. NaOH.
Page 1 of 6
, 8. An endothermic reaction with high activation energy for
the forward reaction is given by which diagram shown in
the graph?
9. Which among the following is a false statement?
(a) Rate of a zero-order reaction is independent of initial concentration of reactant.
(b) Half-life of zero order reaction is inversely proportional to initial concentration of the reactant.
(c) Molecularity of a reaction may be zero or fraction.
(d) For a first order reaction, half-life is independent of initial concentration of reactants.
10. The geometry and magnetic behaviour of the complex [Ni(CO)4] are (at. no. of Ni = 28)
(a) Square planar and paramagnetic. (b) Tetrahedral and diamagnetic
(c) Square planar and diamagnetic. (d) Tetrahedral and paramagnetic.
11. Compounds A and C in the following reaction are ……………...?
(𝐢) 𝐂𝐇𝟑 𝐌𝐠𝐁𝐫 (𝐢𝐢)𝐇𝟐 𝐎 𝐇𝟐 𝐒𝐎𝟒, ∆ (𝐢)𝐁𝟐 𝐇𝟔 (𝐢𝐢) 𝐇𝟐 𝐎𝟐 ,𝐎𝐇−
CH3CHO→ (A) → (B) → (C)
(a) identical (b) positional isomers (c) functional isomers (d) optical isomers.
12. Which of the following cannot be prepared by Sandmeyer’s reaction?
(a) Benzonitrile (b) chlorobenzene (c) bromobenzene (d) iodobenzene.
13. Assertion (A): In K4*Fe(CN)6+, Fe2+ shows diamagnetic behavior according to crystal field theory.
Reason (R): Due to the presence of strong ligand field, ∆o < P, unpaired electrons pair up.
Select the most appropriate answer from the options given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
14. Assertion (A): The cell potential of mercury cell is 1.35 V which remains constant throughout its life.
Reason (R): In mercury cell, the electrolyte is a paste of KOH & ZnO.
Select the most appropriate answer from the options given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
15. Assertion (A): Hydrolysis of ethyl acetate in presence of dilute acid is a reaction of first order
whereas in presence of alkali solution, it is a reaction of second order.
Reason (R): Acid only acts as a catalyst whereas alkali acts as one of the reactants.
Select the most appropriate answer from the options given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Page 2 of 6
