Practice Paper-I. Page 1 of 9

Size: px

Start display at page:

Download "Practice Paper-I. Page 1 of 9"

Philippa Bennett
5 years ago
Views:

1 Practice Paper-I Subject: Chemistry Marks:70 Grade: XII Time: 3 hrs. General Instructions:. All questions are compulsory. Marks of each question are indicated against it. 3. Question numbers to 8 are very short questions, each of mark. Answer these in one word or about one sentence each. 4. Question numbers 9 to 8 are short answer questions of marks each. Answer this in about 30 words each. 5. Question numbers 9 to 7 are short answer questions of 3 marks each. Answer these in about 40 words each. 6. Question numbers 8 to 30 are long answer questions of 5 marks each. Answer these in about 70 words. 7. Use log tables if necessary. Calculators are not permitted.. Write IUPAC name of the following compound. Propanol has higher boiling point than Butane. Why? 3. Lyophilic colloid is more stable than lyophobic colloid. Why? 4. Can we separate a mixture of 5% water and 95% ethanol by simple distillation? Justify your answer. 5. State Henry s Law. 6. Write a reaction which confirms the presence of aldehyde group in Glucose. 7. What is peptide bond? 8. State any one condition under which a bimolecular reaction may be kinetically of the first order. 9. Give four structural differences between DNA and RNA. 0. Aluminium crystallizes in a cubic close packed structure. Its metallic radius is 5pm. (a) What is the length of the side of the unit cell? (b) How many unit cells are there in.00cm 3 of Aluminium?. Explain the following with suitable example (i) n- type semiconductor (ii) F-centres. A first order reaction takes 40 min for 30% decomposition. Calculate t /. Page of 9

2 3. The decomposition of hydrocarbon follows the equation k = (4.5 0s ) e -8000K/T Calculate energy of activation (E a ). 4. Aryl halides are less reactive than alkyl halides towards nucleophillic substitution reactions. Why? 5. Write the mechanism of the following reaction: 6. Write short notes on (i) Hoffmann bromamide degradation reaction (ii) Cannizzaro Reaction 7. Give a chemical test to distinguish between the following (a) Ethyl amine and Diethyl amine (b) Acetaldehyde and Benzaldehyde 8. (a) Calculate the magnetic moment of a divalent ion in aqueous solution if its atomic number is 5. (b )Compare the chemistry of the actinoids with that of lanthanoids with reference to: (i) electronic configuration (ii) oxidation states and What is Lanthanoid contraction? Write its cause and consequences? 9. (i) Give reason of the followings (a) Phenyl methyl ether (or anisole) reacts with HI to give phenol and methyl iodide and not iodobenzene and methyl alcohol. (b) Phenols are more acidic than alcohols. (ii) Name the reagent used in the oxidation of primary alcohol to aldehyde. 0. A 5% solution (by mass) of cane sugar in water has freezing point of 7K. Calculate the freezing point of 5% glucose in water if freezing point of pure water is 73.5 K.. Explain the following terms: (i) Electrophoresis (ii) Peptization (iii) Shape selective catalysis?. Give reason for the following observation (i) Cu + ion is more stable than Cu + in aqueous solution (ii) Cr has maximum melting point in 3d series. (iii) Transition metals and their many compounds act as good catalyst. Page of 9

3 (i) Indicate the steps for the preparation of KMnO 4 from pyrolusite ore. (ii) Write the ionic equations when potassium permanganate reacts with oxalic acid. 3. (a) What is the role of cryolite in the metallurgy of aluminium? (b) The value of Δ f G 0 for formation of Cr O 3 is 540 kjmol and that of Al O 3 is 87 kjmol. Is the reduction of Cr O 3 possible with Al? 4. Give reasons: (i) Hypo phosphorous acid is good reducing agent. (ii) H S is less acidic than H Te. Why? (iii) Chlorine water acts as a bleaching agent. 5. a) Write the IUPAC name for [Co(en) 3 ] (SO 4 ) 3 (b) How many geometrical isomers are possible in the coordination entity [Co (NH 3 ) 3 (NO 3 ) 3 ]? (c) Give the number of unpaired electrons in [Ni(CN) 4 ] -. (Atomic no of Ni = 7) 6. (a) Why do soaps not work in hard water? (b) What are the main constituents of dettol? (c) Name the sweetening agent used in the preparation of sweets for a diabetic patient. 7. a) Name the monomers of biodegradable polymer PHBV. (b) Why the numbers 66 and 6 put in the name of nylon -66 and nylon -6? (c) How vulcanization changes the properties of natural rubber? 8. (a) How will you bring about the following conversions () Propanone to Propene () Benzoic acid to Benzaldehyde (3) Ethanal to 3-Hydroxybutanal (i) (b) Complete the following reactions:- (ii) (a) An organic compound with the molecular formula C 9 H 0 O forms,4-dnp derivative, reduces Tollens reagent and undergoes Cannizzaro reaction. On Page 3 of 9

4 vigorous oxidation, it gives,-benzenedicarboxylic acid. Identify the compound and give the chemical reactions involved. (b) Predict the products formed when cyclohexanecarbaldehyde reacts with following reagents. (i) PhMgBr and then H 3 O + (ii) Zinc amalgam and dilute hydrochloric acid 9. (i) Account for the following: (a) Nitrogen exists as diatomic molecule and phosphorus as P 4. Why (b) Bond dissociation energy of F is smaller than Cl. Why? (c) In aqueous solution HI is stronger acid than HCl. (d) Noble gases have low boiling point. (ii) Draw the structure of XeO 3. (a) Write balanced equations for the following: (i) White phosphorus is heated with concentrated NaOH solution in an inert atmosphere of CO. (ii) The reaction of Cl with hot and concentrated NaOH. (iii) The reaction of platinum with aqua-regia (b) Write the chemical equations involved in Brown ring test for nitrate ion. 30. (a) Resistance of a conductivity cell filled with 0. mol L KCl solution is 00 Ω. If the resistance of the same cell when filled with 0.0 mol L KCl solution is 50 Ω, calculate the conductivity and molar conductivity of 0.0 mol L KCl solution. The conductivity of 0. mol L KCl solution is.9 S/m. (b) Write the cathodic and anodic reactions for the charging of lead storage battery. Or (a) Write the equations involved at anode and cathode in rusting of Iron. (b) Calculate the equilibrium constant for the reaction: Zn(s) + Cu + (aq) Zn + (aq) + Cu(s), Given: E o Zn + /Zn = V and E o Cu + /Cu = V. (c) How much electricity in terms of Faraday is required to produce 0.0 g of Calcium from molten CaCl? Page 4 of 9

5 Practice Paper-II Subject: Chemistry Marks:70 Grade: XII Time: 3 hrs. Gereral instructions;-. All Questions are compulsory.. Q. No. -8 carry marks each. 3. Q. No. 9-8 carry marks each 4. Q. No. 9-7 carry 3 marks each. 5. Q. No carry 5marks each. 6. Use of Log-Table is allowed. 7. Use of calculator is not allowed. What is no. of atoms per unit cell in a body centred cubic structure? A cubic solid is made up of two elements X and Y. Atoms Y are at the corners of the cube and X at body centre. What is formula of compound? 3 A reaction is 50% complete in hours and 75 % complete in 4 hours. What is order of reaction? 4 The rate of reaction X-- Y become 8 times when the concentration of reactant is doubled. Write the rate law for reaction. 5 Name one poisonous gas which can be prepared from chlorine gas. 6 Write common name for -Chloro--methylpropane. 7 What type of aldehyde undergoes cannizaro s reaction? 8 What is name given to linkage that holds two monosaccharide units together? 9 An element crystallizes in FCC structure; 00 g of this element has.408 x 0 4 atoms. If the density of A is 7. g per cc, calculate the edge length of unit cell. 0 Give reason a) Rusting of iron is faster in saline water than in ordinary water. b) Aluminium metal cannot be produced by electrolysis of aq. solution of aluminium salt. What is de-emulsification? How it is brought about? What happens when: a) A beam of light is passed through arsenic sulphide sol. b) KCl is added to Fe (OH) 3 sol. 3 Are all bonds of PCl 5 are equal? Justify your answer. 4 Compare the basic strength of NH 3 and PH 3 giving reason. 5 Which is more acidic ethanol or phenol? Give reason. 6 Write short notes on: a) Williamson s synthesis b) Reimer Tiemann reaction. 7 Give reasons i) pk b value of aniline is higher than that of methylamine. Explain. ii) Aniline does not undergo Friedel craft reactions. 8 Convert i) Nitrobenzene into toluene. ii) Aniline into benzylamine 9 A current of 3.7 Ampere is passed for 6 hours between Pt electrodes in 500 ml of a M solution of Ni (NO 3 ). What will be the molarity of solution at the 3 end of electrolysis? 0 a) Write units for rate constant for a reaction of nd order. b) Show that in case of st order reaction, the time required for 99 % completion is double than that required for 90 % completion. Page 5 of 9

6 a) Describe role of depressant on froth floatation. 3 b) Explain a Mond s process. i) Why N cannot show valency of 5 like Phosphorus present in same group. ii) Why Xe form compound only with oxygen or Flourine only. iii) Why H O exist as liquid while H S exist as gas? 3 Show that [Ni(CN) 4 ] - is square planner and [Ni Cl 4 ] - is tetrahedral with help 3 of valence bond theory. 4 i) Write the order of reactivity of 4 different isomers of butyl chloride by S N mechanism. Give reason. ii) What is ambident nucleophile? Give example. 5 Name components of starch and compare them. 3 6 i) What are main purposes for vulcanization of rubber? ii) What are differences between thermosetting polymers and thermoplastic polymers? 7 Explain the terms with suitable examples i) Cationic detergent ii) Biodegradable detergent iii) Analgesic. 8 i) Calculate the vapour pressure of a solution at 373 K containing 3 g of cane sugar in 33 g of water. ii) Explain the reason for positive deviation of solutions with example. iii) What happens when blood cell is placed in 0.8% NaCl (aq) solution? i) 0.85 % aq solution of NaNO 3 is apparently 90% dissociated at 7 0 C. Calculate its osmotic pressure. (density of solution = g/ml) ii) Prove that osmotic pressure is colligative property. iii) Define Molality. 9 i) Describe the preparation of Potassium dichromate from chromite ore. ii)write its balanced reaction with a) Iron (II) solution b) Iodide ions i) What is the effect of ph on the solution of Potassium dichromate? ii) Why transition metals form no. of alloys? iii) Zn, Hg and Cd are not considered transition metals Why? iv) Why Sc cannot show oxidation state of +? v) Why Transition metals have high enthalpy of atomization? 30 i) Give chemical test to distinguish between a) formaldehyde and acetaldehyde b) methanoic acid and ethanoic acid ii) An organic compound A with molecular formula C 8 H 8 O form an orange red ppt. with,4-dnp reagent and gives Yellow ppt on heating with iodine in presence of NaOH. It neither reduces Tollen s reagent nor Fehling solution. It does not decolorize bromine water. On drastic oxidation with chromic acid, it gives a carboxylic acid B having formula C 7 H 6 O Identify the compounds A, B and explain the reactions involved. i) Give mechanism for addition of HCN on carbonyl group. ii) Draw the structure of semicarbazone of heaxan-3-one. iii) What happens when sodium benzoate is heated with soda lime iv) Give chemical test to distinguish between a) Phenol and benzoic acid b) Acetophenone and Benzophenone. Page 6 of 9 3 3

7 Practice Paper-III Subject: Chemistry Marks:70 Grade: XII Time: 3 hrs. GENERAL INSTRUCTIONS: (i) All questions are compulsory. (ii) Marks for each question are indicated against it. (iii) Questions no.to 8 is very short answer questions and carries marks each. (iv) Questions no.9to 8 is short answer questions and carries marks each. (v) Questions no. 9to 7 are also short answer question and carry 3 marks each. (vi) Questions no.8to30 is long- answer question and carries 5 marks each. (vii) Use long Tables, if necessary. Use of calculators is not allowed. Q.-Why common salt is sometimes yellow instead of being pure white? Q.-Why is it advised to add ethylene glycol to water in a car radiator while driving in a hill station? Q.3-What is the role of desorption in the process of catalysis? Q.4-What is the significance of leaching in the extraction of aluminum? Q.5- Bond angle in PH + 4 is higher than in PH 3? Q.6-What is the basicity of H 3 PO 4? Q.7- Write structures of the compound: -Bromo-4-sec.butyl--methylbenzenene. Q.8- Name the aldehyde which does not give Fehling s solution test. Q.9-What role does the molecular interaction play in the solution of alcohol and water? Q.0- The combustion of a hydrocarbon follows the equation; k= (4.5x 0 s _ ) e _ (8000k) /T. Calculate Ea. Q.- Calculate the mass% of aspirin (C 9 H 8 O 4 ) in acetonitrile (CH 3 CN) when 6.5 of C 9 H 8 O 4 Is dissolved in 450g of CH 3 CN. Q.- Describe the method of refining of nickel. Q.3- Write the mechanism of acidic dehydration of ethanol to ethene. Q.4- Arrange the fallowing set of compounds in order of increasing boiling points: (a) pentan--ol, butane--ol, butane--ol, ethanol, propan--ol. (b) pentan-ol, butane, pentanal, ethoxyethane Q.5- Differentiate between globular and fibrous proteins. Q.6- Write short notes the following: Page 7 of 9

8 (i) Hoffman s-bromamide reactions (ii) carbylamine reaction. Q.7- Why is vitamin A and vitamin C essential to us? Give one source of each. Q.8- Give one chemical test to distinguish between the fallowing pair of compounds: (i) acetophenone and benzophenone. (ii) Aniline and benzylamine. Q.9- An element has a bcc structure with a cell edge of 88pm. The density of the element is 7. g/cm 3. How many atoms are present in 08g of the element? 3 Q.0 the rate of reaction quadruples when the temperature changes from 93K to 33k.Calculate the energy of activation of the reaction assuming that it does not change with temperature. 3 Show that time required for 99% completion of a first order reaction is twice the time required for the completion of 90%. 3 Q.- Explains the following observation: 3 (i) A beam of light passing through a colloidal solution has a visible path. (ii) Passing an electric current through a colloidal solution removes colloidal particles from it. (iii)ferric hydroxide sol coagulates on addition of potassium sulphate. Q.- Arrange the following property for each set: 3 (i) F, Cl, Br, I, increasing bond dissociation enthalpy. (ii) HF, HCl, HBr, HI increasing acid strength. (iii) NH 3, PH 3, AsH 3, SbH 3, BiH 3 - increasing base strength O3. Account for the following: 3 (i) H S acts only as a reducing agent but SO acts both as a reducing agent as well as an oxidizing agent. (ii)sf 6 is known but SH 6 is not known. Explain. (iii) Compound of fluorine with oxygen called fluoride of oxygen and not the oxides of fluorine. Q.4- Give the electronic configuration of the 3 (i) d-orbital s of Ti in [Ti (H O) 6 ] 3+ ion in an octahedral crystal field. (ii) Why is this complex colored? Explain on the basis of distribution of electron in the d-orbital. (iii) How does the color change on heating [Ti (H O) 6 ] 3+ ion? Q.5- How the following conversion can be carried out? 3 (i) -bromopropane to -bromopropane. (ii) Toluene to benzyl alcohol. (iii) Benzene to diphenyl Q.6- (a) - (-NH-CHR-CO -)- n, a homopolymer or a copolymer? (+=3) (b) defined the thermoplastics and thermosetting polymers. Page 8 of 9

9 Q.7- Give the reason for the following? 3 (i) Sulpha drugs work like antibiotic but they are not antibiotics. (ii) Aspirin help in the prevention of heart attack. (iii) Soaps are biodegradable where as detergent are non biodegradable. Q.8-(a) A current of 5 ampere is flowing through a wire for 93 seconds. Calculate the number of electron flowing through the cross section of wire for 93 seconds. (b) Predict the product electrolysis of the fallowing (i) An aqueous solution of AgNO 3 with silver electrodes. (ii) A dilute aqueous solution of H SO 4 with platinum electrodes. (iii) An aqueous solution of CuCl with platinum electrode. (+3=5) Q.9- (a) what are interstitial compound? Why is such compound well known for transition metals? (b) What is meant by lanthanoid contraction? What effect does it have on the chemistry of the elements which fallow lanthanoids? (+3=5) (a) A blackish brown coloured solid A when fused with alkali metal hydroxides in presence of air, produces a dark green coloured compound B, which on electrolytic oxidation in alkaline medium gives a dark purple coloured compound C. Identify A, B and C and write the reaction involved. (b)what happen when an acidic solution of the green compound (B) is allowed to stand for some time? Give the equation involved. (3+=5) Q.30- An organic compounds A on treatment with ethyl alcohol gives carboxylic acid B and compounds C. Hydrolysis of C under acidic condition gives B and D. oxidation of D with KMnO4 also give B. B on heating with Ca(OH) give E with molecular formula C 3 H 6 O. E does not give Tollen s test or reduce Fehling solution but form, 4-dinitrophenyl hydrazone.identify A, B, C, D and E. 5 Identify A to E in the following reactions. ( 5=5) A H + a) CH 3 COCH 3 B CH 3 -C(CH 3 )=CH COCH 3 Pd-BaSO 4 b) C + H D (i) NH -NH (ii) Glycol-KOH conc.hno 3 /H SO 4 c) D E Trinitrotoluene Page 9 of 9

CHEMISTRY. Time : 3 Hrs. Max. Marks : 70

CHEMISTRY. Time : 3 Hrs. Max. Marks : 70 CHEMISTRY Time : 3 Hrs. Max. Marks : 70 General instructions 1. All questions are compulsory. 2. Q.no. 1-5 are very short answer questions & carry 1 marks each Section-A. 3. Q.no. 6-12 are short answer