Reservation and Promotions

CHEMISTRY 

Class XII

Sample Paper - 1  

Time 3 Hr.	SAMPLE PAPER -1  CHEMISTRY (043)	Max. Marks 70
	GENERAL INSTRUCTIONS (a)   There are 33 questions in this question paper with internal choice (b)  SECTION A consists of 16 MCQ carrying 1 mark each. (c)   SECTION B consists of 5 short answer type questions carrying 2 marks each. (d)  SECTION C consists of 7 short answer questions carrying 3 marks each. (e)   SECTION D consists of 2 case based questions carrying 4 marks each. (f)    SECTION E consists of 3 long answer type questions carrying 5 marks each.
	SECTION- A
	The following questions are multiple choice questions with one correct answer. Each question carries 1 mark. There is no internal choice in this section.
1	In the rate equation, when the concentration of reactants is unity then the rate is equal to: (a) Specific rate constant                                            (b) Average rate constant (c) Instantaneous rate constant                                   (d) None of the above	1
2	In alkaline solution, MnO4– changes to (a) MnO42–                                                          (b) MnO2 (c) Mn2O3                                                           (d) MnO	1
3	Why is chlorobenzene resistant to nucleophilic substitution reaction? (a) Partial double bond character in C-Cl bond   (b)  sp2 hybridization of ring carbon (c) Both (i) and (ii)                                                           (d) None	1
4	Radioactive disintegration is an example of (a) first order reaction                                (b) zero order reaction (c) second order reaction                          (d) third order reaction	1
5	Which of the following reagents may be used to distinguish between phenol and benzoic acid ? a) Neutral FeCl3                                                           b) Aqueous NaOH c) Tollen’s reagent                                                      d) Molisch reagent	1
6	Which aldehyde will give Cannizzaro’s reaction? (a) CH3 CH2 CH2CHO                                     (b) CH3CH2 CHCHO (c) (CH3) 3CCHO                                             (d) (CH3) 2CH2CH2 CHO	1
7	Heating of phenyl methyl ether with HI produces a) Iodobenzamide b) phenol c) benzene c) ethyl chloride	1
8	Carbonyl compounds undergo nucleophilic addition because of (a) More stable anion with negative charge on oxygen and less stable carbocation (b) Electrometric effect (c) Electronegativity difference of carbon and oxygen atoms (d) None of the above	1
9	Which of the following statements is incorrect about maltose? (a) It consists of two glucopyranose units. (b) It is a disaccharide. (c) Glycosidic bond between is formed between C1 and C4. (d) It is a non-reducing sugar.	1
10	Which of the following statements about primary amines is ‘false’? (a) Alkylamines are stronger bases than arylamines. (b) Alkylamines are stronger bases than ammonia. (c) Alkylamines react with nitrous acid to produce alcohols. (d) Arylamines react with nitrous acid to produce phenols.	1
11	The property which is not characteristic of transition metals is (a) variable oxidation states. (b) tendency to form complexes. (c) formation of colored compounds. (d) natural radioactivity.	1
12	How many coulombs of electricity is required to reduce 1 mole of Cr2O7 2- in acidic medium? (a) 4 × 96500 C (b) 6 × 96500 C (c) 2 × 96500 C (d) 1 × 96500 C	1
	ASSERTION - REASON TYPE QUESTIONS Read the assertion and reason carefully to mark the correct option out of the options given below: a. If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion. b. If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion. c. If the Assertion is correct but Reason is incorrect. d. If both the Assertion and Reason are incorrect.
13	Assertion (A) : o- nitrophenol has lower boiling point than p-nitrophenol Reason ( R) : o-nitrophenol possess intramolecular hydrogen bonding while p-nitrophenol has intermolecular hydrogen bonding	1
14	Assertion: The order of a reaction can be zero or fractional. Reason: We cannot determine the order from a balanced chemical equation.	1
15	Assertion (A) : The carbon-oxygen bond length in phenol is slightly less than that in methanol. Reason ( R) : The carbon –oxygen bond in phenol has partial double bond character due to + R effect.	1
16	Assertion: Limiting molar conductivity of weak electrolytes can be obtained graphically. Reason: Limiting molar conductivity of weak electrolytes increases with dilution	1
	SECTION- B
	This section contains 5 questions with internal choice in one question. The following questions are very short answer type and carry 2 marks each.
17	Boiling point of water at 750 mm Hg is 99.63°C. How much sucrose is to be added to 500 g of water such that it boils at 100°C.	2
18	What happens when (i)  n-butyl chloride is treated with alcoholic KOH. (ii) Bromobenzene is treated with Mg in the presence of dry ether.	2
19	For a first-order reaction, show that the time required for 99% completion is twice the time required for the completion of 90% of the reaction.	2
20	Enumerate the reactions of D-glucose which cannot be explained by its open chain structure.	2
21	Arrange the following compounds in increasing order of their property as indicated: (i) Acetaldehyde, Acetone, Di-tert-butyl ketone, Methyl tert-butyl ketone (reactivity towards HCN) (ii) CH3CH2CH(Br)COOH, CH3CH(Br)CH2COOH, (CH3)2CHCOOH, CH3CH2CH2COOH (acid strength) Or Give simple chemical tests to distinguish between the following pairs of compounds. (i) Propanol and propanone (ii) Pentan-2-one and pentan-3-one	2
	SECTION C
22	Describe the following reactions giving a chemical equation in each case        ( Attempt any two) (i)              Cannizzaro’s reaction (ii)            Kolbe’s Reaction (iii)          Hell- Volhard Zelinsky Reaction	3
23	A voltaic cell is set up at 25°C with the following half cells : Al/Al3+ (0.001 M) and Ni/Ni2+ (0.50 M) Write an equation for the reaction that occurs when the cell generates an electric current and determine the cell potential. E0 (Ni2+ /Ni) = −0.25V and E0 (Al3+ /Al) = −1.66V (Log 8 × 10-6 = -0.54)	3
24	The following data were obtained during the first order thermal decomposition of N2O5 (g) at constant volume: N2O5 (g)    → N2O4 (g)  + O2 (g) S.No. Time/ (s) Total pressure/(atm) 1 0 0.5 2 100 0.512	3
25	Explain the following : (i)              Low spin octahedral complexes of nickel are not known. (ii)            The π-complexes are known for transition elements only	3
26	How the following conversions can be carried out: (i)              2-Bromopropane to 1-bromopropane (ii)            Toluene to benzyl alcohol (iii)          Benzene to diphenyl	3
27	What happens when D-glucose is treated with the following reagents? (i) HI                                  (ii) Bromine water                          (iii) HNO3	3
28	Give reasons for the following: (i) Phenol is more acidic than methanol. (ii) The C—O—H bond angle in alcohols is slightly less than the tetrahedral angle (190°28′). (iii) (CH3) 3C—O—CH3 on reaction with HI gives (CH3) 3C—I and CH3—OH as the main products and not (CH3) 3C—OH and CH3—I.	3
	SECTION D
	The following questions are case based questions. Read the case carefully and answers the questions that follow:
29	Metallic conductance involves movement of electrons whereas electrolytic conductance involves movement of ions. Specific conductance increases with increase in concentration whereas molar conductivity decreases with increase in concentration. We use AC current for measuring resistance of ionic solution in conductivity cell using platinized Pt electrode. Resistance of ionic solution is measured by Wheatstone bridge. Ʌm0 of strong electrolytes can be obtained by extrapolation. Kohlrausch law helps to determine limiting molar conductivity of weak electrolyte, degree of ionization ( ) and their dissociation constants. (a)   Out of 0.1 M and 0.01 M KCl, which has higher specific conductance and why? (b)   Ag at 300C or 600C will have higher conductance and Why? (c)   Calculate Ʌm of 0.1 KCl if resistance is 100 ohms and cell constant is 1.29cm-1 Or What will be the degree of dissociation of CH3COOH if 0.01 M has Ʌm 40 Scm2mol-1 and Ʌm0 is 400 Scm2mol-1?	4
30	KMnO4 and K2Cr2O7 are the most important chemicals which are used as oxidizing agents and disinfectants. K2MnO4 is prepared by fusing MnO2 with KOH in presence of O2. K2MnO4 is electrolyzed to get purple colored KMnO4. Na2CrO4 is converted into Na2Cr2O7 by reacting with KCL to get K2Cr2O7, orange colored solid, soluble in water, changes to yellow colored CrO42- in basic medium, KMnO4 acts as oxidizing agent in acidic, neutral as well as basic medium. In acidic medium it converts Fe2+ to Fe3+, Sn2+ to Sn4+, C2O42- to CO2. In basic medium it converts I-1 to IO3-. K2Cr2O7 acts as an oxidizing agent only in acidic medium, converts H2S to S, SO2 to SO42-, I-1 to I2. Lanthanoids and Actinoids belongs to f block elements with general electronic configuration (n-2)f 1-14(n-1)d0-2ns2. All actinoids are radioactive. Both show contraction in atomic and ionic radii but actinoids contraction is more than lanthanoids contraction. Lanthanoids show +3 oxidation state, few elements show +2 and +4 oxidation state also. Actinoids show +3, +4, +5, +6, +7 oxidation states. (a)   Which Lanthanoids show +4 oxidation state? (b)   Which oxidation states are shown by actinoids? (c)   Define Lanthanoids contraction. (d)   How many moles of Fe2+ get oxidized by 1 mole Cr2O72- in acidic medium? Give balanced chemical equation. Or What happens when sodium chromate reacts with conc. H2SO4? Write balanced chemical equation.	4
	SECTION E
	The following questions are case based questions. Read the case carefully and answers the questions that follow:
31	(a)   (i) At the same temperature, CO2 gas is more soluble in water than O2 gas. Which one of them will have higher KH value and Why? (ii)How does the size of the blood cells change when placed in an aqueous solution containing more than 0.9% (mass/ volume) sodium chloride? (iii)1 molal aqueous solution of an electrolyte A2B3 is 60 % ionized. Calculate the boiling point of the solution. Or (i)              The vapor pressure A and B at 250C are 75 mm Hg, 25mm Hg respectively. If A and B are mixed with such that the mole fraction of A in the mixture is 0.4, then calculate the mole fraction of B in vapor phase. (ii)            Define colligative property. Which colligative property is preferred for the molar mass determination of macromolecules? (iii)          Why are equimolar solutions of sodium chloride and glucose not isotonic?	5
32	Account for following: (Attempt any five) (i) Actinoid contraction is greater than lanthanoid contraction. (ii)  Of the d4 species, Cr2+ is strongly reducing while Mn3+ is strongly oxidizing. (ii) Cobalt (II) is stable in an aqueous solution, but in the presence of complexing reagents, it is easily oxidized. (iv)           Zr and Hf  have almost identical radii. (v)             The highest oxidation state is exhibited in oxyanions of a metal. (iv) Complete following chemical equations- 3MnO4 2- +4H + → Cr2O7 2- + Fe2+ + H+ →	5
33	A compound 'A' (C3H7NO) on reaction with Br2 and KOH gives 'B'. 'B' on reaction with CHCl3, and KOH gives ‘C’. ‘B’ reacts with Heinsberg’s reagent to form D which is soluble in KOH. Identify A to D. Or (i)Although the amino group is ortho and para directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline. (ii) Ethylamine is soluble in water, whereas aniline is not. (iii) Diazonium salts of aromatic amines are more stable than those of aliphatic amines. (iv) Arrange the following. (a)   In increasing order of basic strength, C6H5NH2, C6H5N(CH3) 2, (CH3) 2NH and CH3NH2 (b)   In increasing order of boiling point, C2H5OH, (CH3) 2NH, C2H5NH2	5