Sample Paper-3 Chemistry Class 12

 

 

SAMPLE PAPER -3 CLASS: XII SUBJECT: CHEMISTRYTHEORY (043) TIME: 3 Hrs                                                                                         MM: 70

 

General Instructions:

Read the following instructions carefully.

(a)  There are 33 questions in this question paper with internal choice.

(b)  SECTION A consists of 16 multiple -choice questions carrying 1 mark each.

(c)  SECTION B consists of 5 short answer 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 questions carrying 5 marks each.

(g)  All questions are compulsory.

(h)  Use of log tables and calculators is not allowed.

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.	The amount of electricity required to deposit 1 mol of aluminum from a solution of AlCl3 will be (a)0.33F (b)1F (c)3F (d) 1 ampere
2.	Tertiary amines have lowest boiling points amongst isomeric amines because: (a) they have highest molecular mass. (b) they do not form hydrogen bonds. (c) they are more polar in nature (d) they are most basic in nature
3.	What is the building block of a nucleic acid? a) Amino acid b) Nucleoside c) Monosaccharide d) Nucleotide
4.	Which of the following will not give aldol condensation? (a) Phenyl acetaldehyde(b) 2-Methylpentanal (c) Benzaldehyde (d) 1-Phenylpropanone
5.	Mischmetal contains: (a) a lanthanoid element and Zinc         (b) an actinoid element and Zinc (c) a lanthanoid element and iron          (d) an actinoid element and Mg
6.	CH3CH2OH can be converted into CH3CHO by: (a)  catalytic hydrogenation                                    (b)treatment with LiAlH4 (c) treatment with pyridinium chlorochromate        (d) treatment with KMnO4
7.	The rate constant of a reaction is 1.2 x 10-2s-1, the order of reaction is: (a) 0 (b) 1(c) 0.5 (d) 2
8.	Cu+ is less stable than Cu2+ in aqueous solution. This is because of (a) More negative Hydration enthalpy of Cu+ ion (b) More negative Hydration enthalpy of Cu2+ ion (c) Less negative Hydration enthalpy of Cu2+ ion (d) Less enthalpy atomization of Cu
9.	A first order reaction has a rate constant1.15×10-3 s-1. How long time will 5g of this reactant take to reduce to 3g? (a)444 (b) 400s (c) 528s (d) 669s
10.	Arrange the following compounds in increasing order of boiling point: Propan-1- ol, butan-2-ol, butan-1-ol, pentan-1-ol (a) Propan-1 -ol, butan-2-ol, butan-1 -ol, pentan-1-ol (b) Propan-1 -ol, butan-1 -ol, butan-2-ol, pentan-1 -ol (c) Pentan-1 -ol, butan-2-ol, butan-1 -ol, propan-1 -ol d) Pentan-1 -ol, butan-1 -ol, butan-2-ol, propan-1 -ol
11.	Which one of the following compounds is more reactive towards SN1 reaction? (a)   CH2=CHCH2Br (b) C6H5CH2Br (c) C6H5CH (C6H5)Br (d) C6H5CH(CH3) Br
12.	Methyl ketones are usually characterized through (a) Tollens's reagent (b) Iodoform test (c) Schiff’s test (d) Benedict test.
	In questions (13 to 16), Given below are two statements labeled as Assertion (A) and Reason (R). Select the most appropriate answer in questions 13 to 16, 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.
13.	Assertion (A): D (+) Glucose is dextrorotatory in nature. Reason (R): ‘D’ represents its dextrorotatory nature.
14.	Assertion (A): During electrolysis of aqueous copper sulphate solution using copper electrodes hydrogen gas is released at the cathode. Reason(R): The electrode potential of Cu2+/Cu is greater than H+/ H2
15.	Assertion (A): Phenol is more reactive than benzene towards electrophilic substitution reaction. Reason (R): In the case of phenol, the intermediate carbocation is more resonance stabilized.
16.	Assertion (A): (CH3)3C-COOH does not undergo HVZ reaction. Reason (R): It does not contain any α- hydrogen

 

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.	Define Osmotic Pressure. Why is osmotic pressure used for the determination of molar masses of macromolecules like protein?
18.	A reaction is second order in A and first order in B. (i) Write the differential rate equation. (ii) How is the rate affected on increasing the concentration of A three times?
19.	Account for the following: (i) The C – Cl bond length in chlorobenzene is shorter than that in CH3– Cl (ii) Grignard reagent should be prepared under anhydrous conditions.
20.	Arrange the following compounds in increasing order of their property as indicated: (a) CH3COCH3, C6H5COCH3, CH3CHO (reactivity towards nucleophilic addition reaction) (b)  Cl—CH2—COOH, F—CH2—COOH, CH3—COOH (acidic character) OR Convert the following: (a) Benzene to m-nitrobenzaldehyde (b) Bromobenzene to benzoic acid
21.	Differentiate between the following: (i) Amylose and amylopectin (ii) Peptide linkage and glycosidic linkage

 

SECTION C

This section contains 7 questions with internal choice in one question. 

The following questions are short answer types and carry 3 marks each.

22.	For the standard cell Cu(s)/Cu2+(aq) || Ag+(aq)/Ag(s) (i) Identify the cathode and the anode as the current is drawn from the cell. (ii) Write the reaction taking place at the electrodes. (iii) Calculate the standard cell potential. E°(Cu2+/Cu) = +0.34V, E° (Ag+/Ag)= +0.80 V
23.	Give the formula of each of the following coordination entities: (a)Co3+ion is bound to one Cl-, one NH3molecule and two bidentate ethylene diamine (en) molecules. (b) Ni2+ion is bound to two water molecules and two oxalate ions. Write the name and magnetic behaviour of each of the above coordination entities.
24.	Write the name of the reaction, structure and IUPAC name of the product formed when (any 2): (a) phenol reacts with CHCl3in the presence of NaOH followed by hydrolysis. (b)  CH3CH2CH(CH3)CH(CH3)ONa reacts with C2H5Br. (c)  CH3CH2CN reacts with stannous chloride in the presence of hydrochloric acid followed by hydrolysis.
25.	The decomposition of phosphine, 4PH3(g) ®P4(g) + 6H2(g) has the rate law, Rate = k[PH3]. The rate constant is 6.0 × 10-4 s-1 at 300 K and activation energy is 3.05 × 105J mol-1. Calculate the value of rate constant at 310 K. [Given: R = 8.314 J K-1mol-1]
26.	(a)Haloalkanes undergo nucleophilic substitution whereas haloarenes do not undergo it easily. Explain. (b) The product formed during SN1 reaction is a racemic mixture. Explain.
27.	An organic compound ‘A’ which has characteristic odor, on treatment with NaOH forms two compounds ‘B’ and ‘C’. Compound ‘B’ has the molecular formula C7H8O which on oxidation CrO3gives back compound ‘A’. Compound ‘C’ is the sodium salt of the acid. ‘C’ when heated with soda lime yields an aromatic hydrocarbon ‘D’. Deduce the structures of ‘A’, ‘B’, ‘C’ and ‘D’.
28.	(a)Complete the following statement: In sucrose, the two monosaccharide units are held together by _____(A) linkage between C1of _______(B) and C2 of _______ (C). Identify A, B & C. (b) Sucrose is dextrorotatory, but after hydrolysis the mixture is levorotatory.

 

SECTION D

The following questions are case-based questions. Each question has an internal choice and carries 4 (1+1+2) marks each. Read the passage carefully and answer the questions that follow.

29.	Complex compounds play an important role in our daily life. Werner’s theory of complex compounds says every metal atom or ion has primary valency (oxidation state) which is satisfied by negatively charged ions, ionizable where secondary valency (coordination number) is non-ionizable, satisfied by ligands (+ve, –ve, neutral) but having lone pair. Primary valency is non-directional, and secondary valency is directional. Complex compounds are named according to the IUPAC system. Valence bond theory helps in determining shapes of complexes Based on hybridization, magnetic properties, outer or inner orbital complex. Complex show ionization, linkage, solvate and coordination isomerism also called structural isomerism. Some of them also show stereoisomerism i.e. geometrical and optical isomerism. Ambidentate ligand are essential to show linkage isomerism. Polydentate ligands form more stable complexes then unidentate ligands. There are called chelating agents. EDTA is used to treat lead poisoning, cis-platin as anticancer agents. Vitamin B12 is complex of cobalt. Haemoglobin, oxygen carrier is complex of Fe2+and chlorophyll essential for photosynthesis is complex of Mg2+. (a) What is the oxidation state of Ni in [Ni(CO)4]? OR      Write the coordination number in the given complex:       [Cr(H2O)2(C2O4)2]- (b) Indicate the type of isomerism exhibited by the following complex:      [Co(NH3)5(NO2)](NO3)2 (c)   Out of cis – [Pt(en)2Cl2]2+and trans (Pt(en)2Cl2)2+which one shows optical isomerism and why?
30.	Conductors allow the passage of electric current through them. Metallic and electrolytic are the two types of conductors. Current carriers in metallic and electrolytic conductors are free electrons and free ions respectively. Specific conductance or conductivity of the electrolyte solution is given by the relation: Ƙ= c x l/A where c = 1/R is the conductance and l/A is the cell constant. The molar conductance of strong electrolytes depends on concentration: Λm= Λ°m− b√c,Λm= molar conductance at infinite dilution, c= concentration of the solution, b = constant. The degree of dissociation of weak electrolytes is calculated as:α = 𝜆𝑚/𝜆𝑚∞ (a) Out of specific conductance and molar conductance, which one of the following decreases on dilution of electrolyte solution and why? (b) The resistance of a conductivity cell containing 0.001M KCl solution at 298 K is 1500 M. What is the cell constant if the conductivity of 0.001M KCl solution at 298 K is 0.146 × 10−3S cm−1? (c) Calculate ⋀°m NH4OH from the following values.⋀°m for Ba(OH)2,BaCl2, NH4Cl are 257.6, 240.6, 129.8 S cm2mol-1respectively. OR (i)Write the correct order of molar conductance at infinite dilution for LiCl, NaCl and KCl. (ii)State Kohlrausch’s law.

SECTION E

The following questions are long answer type and carry 5 marks each. 

All questions have an internal choice.

31.	(a) What is the effect of pressure on the solubility of glucose in water? (b) Smith collected a 20 mL each of fresh water and sea water. He observed that one sample labeled “A” froze at 0 oC while the other “B” at -1.5oC. He forgot which of the two, “A” or “B” was sea water. Help him identify which container contains sea water, giving rationalization for your answer. (c)  Calculate Van't Hoff factor for an aqueous solution of K3 [Fe(CN)6] if the degree of dissociation (α) is 0.852. What will be boiling point of this solution if its concentration is 1 molal? (Kb=0.52 K kg/mol) OR (a)  What type of deviation from Raoult’s Law is expected when phenol and aniline are mixed with each other? What change in the net volume of the mixture is expected? Graphically represent the deviation. (b)  The vapour pressure of pure water at a certain temperature is 23.80 mm Hg. If 1 mole of a non- volatile non- electrolytic solute is dissolved in 100g water, Calculate the resultant vapour pressure of the solution.
32.	(a) Account for the following: (i) pKbof aniline is more than that of methylamine. (ii)Although amino group is o, p−directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m- nitroaniline. (b) Arrange the following in: (i) In decreasing order of basic strength in gas phase: C2H5NH2, (C2H5)2NH, (C2H5)3N and NH3 (ii) increasing order of solubility in water C2H5Cl, C2H5NH2, C2H5OH (iii) decreasing boiling point CH3COOH, C2H5OH, CH3NH2, CH3OCH3 OR (a) Describe a method for the identification of primary, secondary and tertiary amines. Also write chemical equations of the reactions involved. (b)  Write short notes on the following: (i) Carbylamine reaction (ii) Hofmann’s bromamide reaction
33.	Attempt any five of the following: (a) Transition metals and many of their compounds show paramagnetic behaviour.Why? (b) The enthalpies of atomization of transition metals are high.Why? (c) Transition metals form alloys and interstitial compounds. Why? (d)  The second ionization enthalpies of chromium and manganese are 1592 and 1509 kJ/mol respectively. Explain the lower value of Mn. (e)  Give two similarities in the properties of Sc and Zn. (f)  What is actinoid contraction? What causes actinoid contraction? (g) What is the oxidation state of manganese in manganate and permanganate ion?