FIRST TERM EXAMINATION CLASS XII CHEMISTRY THEORY SET A

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1 FIRST TERM EXAMINATION CLASS XII CHEMISTRY THEORY TOTAL NO. OF PRINTED PAGE 3 SET A TIME ALLOWED 3 HRS. MAXIMUM MARKS 70 GENERAL INSTRUCTIONS i. All questions are comuplsory ii. Marks for each questions are indicated against it iii. Question no. 1 to 5 are very shor-answer questions, carrying 1 mark each. Answer these in one word or about one sentence each. iv. Question no. 6 to 12 are short answer questions, carrying 2 marks each. Answer these in about 30 words each. v. Question no. 13 to 24 are short answer question of 3 marks each. Answer these in about 40 words each. vi. Question no are long answer questions of 5 marks each. Answer these in about 70 words each. vii. Supply proper diagram in support of your answer i. Use Log Tables, if necessary. Use of calculators is not permitted 1. If three elements A, B and C crystallise in a cubic solid lattice with A atoms at the corner, B atoms at the cube centre and C atoms at the edges, then what is the formulae of the crystal? 2. What is meant by the term peptisation? 3. Why Zn, Cd and Hg are not considered as transition element? 4. Give the IUPAC name of Na 3 [Co(NO 2 )]? 5. An isotope of an element is present in group 18 and 5 th period of the periodic table. What will be the position occupied by its daughter element in the periodic table if it emits one particle per atom? 6. Calculate the wavelength of an object moving with a velocity of 3 X 10 4 m/sec given the mass of object = 6 x kg. 7. Explain why the bond order of N 2 is greater than N 2 + ; but the bond order of O 2 is less than O 2 +?

2 8. An elemnt has a body centered cubic(bcc) structure with a cell- edge of 288 pm. The dentsity of the element is 7.2 gm/cc. How many atoms are present in 208 gm of the element? gm of a nonelectrolyte solute dissolved in 50.5 gm of benzene lowered the freezing point of the benzene by 0.40 K. The freezing point depression constant of benzene is 5.12 K kg / mol. Find the molecular mass of the solute and the atomicity of the molecule, if the atomic mass of the solute is Predict in which of the following case the entropy will increase or decrease: a. a liquid crystallizes into solid b. The temperature of the crystalline solid changes from 0 K to 115 K 11. How would you explain the sharp increase in molar conductivity of a weak electrolyte on dilution? How is themolar conductivity related to the degree of dissociationof a sparingly soluble salt? 12. Write the balanced equatioins for the following reactions: a. Ca 3 P 2 + water b. P 4 + KOH + water 13. The Quantised energy of electron in hydrogen atom for the nth energy level is given by: E n = x 10 5 / n 2 J per mole Calculate the minimum energy required to remove the electron completely from hydrogen atom when its quantised energy level n equals 2. What should be the wavelength of light the can be used to cause this transition? 14. Aluminium crystallises in a cubic close packed structure. Its metallic radius is 125 pm. a. What is the length of the side of the unit cell b. How many unit cells are there in 1.00 cubic cm of Aluminium 15. Two elements A and B form compounds having molecular formula AB 2 and AB 4 When dissolved in 20 gm. Of benzene 1 gm of AB 2 lowers the freezing point by 2.3 K, while 1.0 gm of AB 4 lowers it by 1.3 K The molar depression constant for benzene is 5.1 Kg per mole Calculate the atomic mass of A and B? 16. A reaction is first order in A and second order with respect to B: a. Write differential rate equation b. How is the rated affected if the concentratioin of B is tripled c. How is the rate effected when the concentration of both A and B are doubled. 17. The activation energy of a reaction is 75.2 Kj/mole in the absence of a catalyst and kj/mole in presentce of the catalyst. How many times will the rate of rection grow in the presence of the catalyst if the reactioin proceeds at 25 o C? (R=8.314 J/K/mole) 18. Explain what is observed:

3 a. when a beam of light is passed through a colloidal sol b. an electrolyte of NaCl is added to ferric hydroxide sol c. electric current is passed through a colloidal sol. 19. Give reason for each of the following observation: a. Noble gases are mostly chemically inert b. Nitrogen does not form pentahalide c. Bismuth is a strong oxidising agent in pentavalent state 20 a. Ni +2 ion is thermodynamically more stable tha Pb 2+. b. Most of the transition metal ions are coloured in solution c. Transition metals are well-known to form complexes. 21 Describe the prepration of Potassium Dichromate from chromite ore with chemical equation and the structure of dichromate ion. 22. Draw a sketch to show the splitting of d-orbitals in an octahedral crystal field. State for a d 6 ion how the actual configuration of the split d-orbitals in an octahedral crystal fiedl is decided by the relative values of o and P. 23. a. How can the course of a reaction be known by using radioisotopes. b. Describe the principle of breeder reactor. c. Complete the following equation:.(,2n) 211 At a. Identify and idicate the presence of centre of chirality, if any, in the following molecules: i. 2-aminobutane ii. 1,2-dichloropropane b. Employing Cahn-Ingold-Prelog sequence rule indicate the priority sequence: -methyl, -ethyl, -isopropyl, - terbutyl. 25. a. What is meant by an entropy driven reaction? How can a reaction with positive enthalpy and entropy changes can be made entropy driven. b. Calculate the standard Gibb's energy change for the formation of propane C 3 H 8 at 298 K. Given :enthalpy of formation of propane: kj/mole, molar entropy of propane, Hydrogen and Carbon : 270.2, , 5.74 J/K/mole respectively 26. i. Explain the mechanism of Corrision. ii. The resistance of 0.01 M acetic acid solution is observed to be 2220 ohm when measured with a cell of cell constant per cm. calculate the degree of dissociation of acetic acid at this concentration. Also find the dissociation constant of acetic acid. Given: conductance of H + = /ohm/cm.sq/mole and of CH 3 COO - = 40.9 /ohm/cm.sq/mole 27. Explain the following statement:

4 a. Sulphur exhibits greater tendency for catenation than selenium b. Tin (II) is a reducing agent where as Pb (II) is oxidising agent. c. Silicon is an insulator but silicon doped with phosphorous acts as a semi-conductor. d. Trisilyl ammine is planar but trimethylammine is pyramidal. e. PH 3 is weaker base than NH 3. Or// a. Assign a reason for each of the following statement: i. Anhydrous AlCl 3 acts as a catalyst in many organic reaction ii. All the bonds in a molecule of PCl 5 are not equal iii. Hydrogen Fluoride is a weaker acid than hydrogen chloride in aquoeous solution b. Write structure for the following: i. IF 5 ii. XeOF 2

5 FIRST TERM EXAMINATION CLASS XII CHEMISTRY THEORY TOTAL NO. OF PRINTED PAGE 3 SET B TIME ALLOWED 3 HRS. MAXIMUM MARKS 70 GENERAL INSTRUCTIONS i. All questions are comuplsory ii. Marks for each questions are indicated against it iii. Question no. 1 to 5 are very shor-answer questions, carrying 1 mark each. Answer these in one word or about one sentence each. iv. Question no. 6 to 12 are short answer questions, carrying 2 marks each. Answer these in about 30 words each. v. Question no. 13 to 24 are short answer question of 3 marks each. Answer these in about 40 words each. vi. Question no are long answer questions of 5 marks each. Answer these in about 70 words each. vii. Supply proper diagram in support of your answer viii. Use Log Tables, if necessary. Use of calculators is not permitted 1. If three elements A, B and C crystallise in a cubic solid lattice with A atoms at the corner, B atoms at the cube centre and C atoms at the edges, then what is the formulae of the crystal? 2. How can colloidal solution of sulphur in water be prepared? 3. Out of Cr 2+ and Cr 3+ which is more stable and why? 4. Give the IUPAC name of Na 3 [Co(NO 2 )]? 5. An isotope of an element is present in group 18 and 5 th period of the periodic table. What will be the position occupied by its daughter element in the periodic table if it emits one particle per atom? 6. Calculate the wavelength of an object moving with a velocity of 3 X 10 4 m/sec given the mass of object = 6 x kg. 7. Explain why the bond order of N 2 is greater than N + 2 ; but the bond order of O 2 is less than O + 2? 8. Calculate the value of Avogadro constant from the following data: Denstity of NaCl = gm/ cu.cm. Distance between Na and Cl ion in NaCl =281 pm.

6 gm of a nonelectrolyte solute dissolved in 50.5 gm of benzene lowered the freezing point of the benzene by 0.40 K. The freezing point depression constant of benzene is 5.12 K kg / mol. Find the molecular mass of the solute and the atomicity of the molecule, if the atomic mass of the solute is State the third law of thermodynamics and its implication 11. How would you explain the sharp increase in molar conductivity of a weak electrolyte on dilution? How is themolar conductivity related to the degree of dissociationof a sparingly soluble salt? 12. Write the balanced equatioins for the following reactions: a. Ca 3 P 2 + water b. P 4 + KOH + water 13. The Quantised energy of electron in hydrogen atom for the nth energy level is given by: E n = x 10 5 / n 2 J per mole Calculate the minimum energy required to remove the electron completely from hydrogen atom when its quantised energy level n equals 2. What should be the wavelength of light the can be used to cause this transition? 14. Aluminium crystallises in a cubic close packed structure. Its metallic radius is 125 pm. a. What is the length of the side of the unit cell b. How many unit cells are there in 1.00 cubic cm of Aluminium 15. Two elements A and B form compounds having molecular formula AB 2 and AB 4 When dissolved in 20 gm. Of benzene 1 gm of AB 2 lowers the freezing point by 2.3 K, while 1.0 gm of AB 4 lowers it by 1.3 K The molar depression constant for benzene is 5.1 Kg per mole Calculate the atomic mass of A and B? 16. A reaction is first order in A and second order with respect to B: a. Write differential rate equation b. How is the rated affected if the concentratioin of B is tripled c. How is the rate effected when the concentration of both A and B are doubled 17. The activation energy of a reaction is 75.2 Kj/mole in the absence of a catalyst and kj/mole in presentce of the catalyst. How many times will the rate of rection grow in the presence of the catalyst if the reactioin proceeds at 25 o C? (R=8.314 J/K/mole) 18. Explain the term: a. Electrophoresis b. Coagulation c. Tyndall effect 19. Give reason for each of the following observation:

7 a. Noble gases are mostly chemically inert b. Nitrogen does not form pentahalide c. Bismuth is a strong oxidising agent in pentavalent state 20. Account for the following: a. Ni +2 ion is thermodynamically more stable tha Pb 2+. b. Transition metals forms a number of interstitial compounds. c. Silver halide founds use in photography 21. Describe the prepration of Potassium Dichromate from chromite ore with chemical equation and the structure of dichromate ion. 22. Draw a sketch to show the splitting of d-orbitals in an octahedral crystal field. State for a d 6 ion how the actual configuration of the split d-orbitals in an octahedral crystal fiedl is decided by the relative values of o and P. 23. a.how can the course of a reaction be known by using radioisotopes. c. Describe the principle of breeder reactor. d. Complete the following equation:.(,2n) 211 At a. Identify and idicate the presence of centre of chirality, if any, in the following molecules: i. 2-aminobutane ii. 1,2-dichloropropane b. Employing Cahn-Ingold-Prelog sequence rule indicate the priority sequence: -methyl, -ethyl, -isopropyl, - terbutyl. 25. Explain the following statement: a. Sulphur exhibits greater tendency for catenation than selenium b. Tin (II) is a reducing agent where as Pb (II) is oxidising agent. c. Silicon is an insulator but silicon doped with phosphorous acts as a semiconductor. d. Trisilyl ammine is planar but trimethylammine is pyramidal. e. PH 3 is weaker base than NH 3. Or// a. Assign a reason for the following statements: i. SF 6 is easily hydrolysed. ii. In solid PCl 5 exists as an ionic compound iii. CO 2 and SiO 2 are not isostructural. b. Arrange the following in the decreasing order of the property indicated i. H 2 O, H 2 S, H 2 Se, H 2 Te -- boiling point ii. F,Cl, Br, and I --- Bond energy 26. a. Predict the product of electrolysis in the following:

8 i. An aqueous solution of silver nitrate with siver electrodes ii. A dilute solution of sulphuric acid with platinum electrodes iii. An aqueous solution of CuCl 2 with platinum electrodes. b. The resistance of a conductivity cell containing M KCl solution at 298 K is 1500 ohm. What is the cell constant if the conductivity of M KCl solution at 298 K is x 10-3 S/cm 27. a. Give reason: i. Many thermodynaically feasible reactions do not occur under ordinary condition. ii. An exothermic reaction is sometimes not spontaneous. b. The standard Gibbs energy Change values at 1773 K are given for the following reactions: 4 Fe + 3 O 2 2Fe 2 O 3 G = Kj/mole 4 Al + 3 O 2 2 Al 2 O 3 G = Kj/mole 2 CO + O 2 2CO 2 G= -515Kj/mole Find out the possibility of reducing Fe 2 O 3 and Al 2 O 3 with CO at this temperature.

9 FIRST TERM EXAMINATION CLASS XII CHEMISTRY THEORY TOTAL NO. OF PRINTED PAGE 3 SET C TIME ALLOWED 3 HRS. MAXIMUM MARKS 70 GENERAL INSTRUCTIONS i. All questions are comuplsory ii. Marks for each questions are indicated against it iii. Question no. 1 to 5 are very shor-answer questions, carrying 1 mark each. Answer these in one word or about one sentence each. iv. Question no. 6 to 12 are short answer questions, carrying 2 marks each. Answer these in about 30 words each. v. Question no. 13 to 24 are short answer question of 3 marks each. Answer these in about 40 words each. vi. Question no are long answer questions of 5 marks each. Answer these in about 70 words each. vii. Supply proper diagram in support of your answer viii. Use Log Tables, if necessary. Use of calculators is not permitted 1. If three elements A, B and C crystallise in a cubic solid lattice with A atoms at the corner, B atoms at the cube centre and C atoms at the edges, then what is the formulae of the crystal? 2. Why do colloidal solution exhibit tyndall effect? 3. How many unpaired electrons are there in Ni 2+? 4. Give the IUPAC name of Na 3 [Co(NO 2 )]? 5. An isotope of an element is present in group 18 and 5 th period of the periodic table. What will be the position occupied by its daughter element in the periodic table if it emits one particle per atom? 6. Calculate the wavelength of an object moving with a velocity of 3 X 10 4 m/sec given the mass of object = 6 x kg. 7. Explain why the bond order of N 2 is greater than N 2 + ; but the bond order of O 2 is less than O 2 +?

10 8. If the radius of the octahedral void is r and radius of the atoms in close packing is R derive the relationship between r and R? gm of a nonelectrolyte solute dissolved in 50.5 gm of benzene lowered the freezing point of the benzene by 0.40 K. The freezing point depression constant of benzene is 5.12 K kg / mol. Find the molecular mass of the solute and the atomicity of the molecule, if the atomic mass of the solute is How is the concept of coupling of reactions is useful to explain the occurrednce of a nonspontaneous reaction? 11. How would you explain the sharp increase in molar conductivity of a weak electrolyte on dilution? How is themolar conductivity related to the degree of dissociationof a sparingly soluble salt? 12. Write the balanced equatioins for the following reactions: a. Ca 3 P 2 + water b. P 4 + KOH + water 13. The Quantised energy of electron in hydrogen atom for the nth energy level is given by: E n = x 10 5 / n 2 J per mole Calculate the minimum energy required to remove the electron completely from hydrogen atom when its quantised energy level n equals 2. What should be the wavelength of light the can be used to cause this transition? 14. Analysis shows that nickel oxide has formulae Ni O 1.00 What fractions of nickel exist as Ni +2 and Ni +3? 15. Two elements A and B form compounds having molecular formula AB 2 and AB 4 When dissolved in 20 gm. Of benzene 1 gm of AB 2 lowers the freezing point by 2.3 K, while 1.0 gm of AB 4 lowers it by 1.3 K The molar depression constant for benzene is 5.1 Kg per mole Calculate the atomic mass of A and B? 16. A reaction is first order in A and second order with respect to B: a. Write differential rate equation b. How is the rated affected if the concentratioin of B is tripled c. How is the rate effected when the concentration of both A and B are doubled 17. The activation energy of a reaction is 75.2 Kj/mole in the absence of a catalyst and kj/mole in presentce of the catalyst. How many times will the rate of rection grow in the presence of the catalyst if the reactioin proceeds at 25 o C? (R=8.314 J/K/mole) 18. What is meant by shape selective catalysis. How is it used in obtaining gasoline from alcohol? Name the catalyst used in this process. 19. Give reason for each of the following observation: a. Noble gases are mostly chemically inert b. Nitrogen does not form pentahalide c. Bismuth is a strong oxidising agent in pentavalent state 20. Account for the following:

11 a. The transition elemnts exhibit high enthalpies of atomisation b. Ni +2 ion is thermodynamically more stable tha Pb 2+. c. A transition element forms alloy with other transition element. 21.Describe the prepration of Potassium Dichromate from chromite ore with chemical equation and the structure of dichromate ion. 22. Draw a sketch to show the splitting of d-orbitals in an octahedral crystal field. State for a d6 ion how the actual configuration of the split d-orbitals in an octahedral crystal fiedl is decided by the relative values of o and P. 23. a. How can the course of a reaction be known by using radioisotopes. b. Describe the principle of breeder reactor. c. Complete the following equation:.(,2n) 211 At a. Identify and idicate the presence of centre of chirality, if any, in the following molecules: i. 2-aminobutane ii. 1,2-dichloropropane b. Employing Cahn-Ingold-Prelog sequence rule indicate the priority sequence: -methyl, -ethyl, -isopropyl, - terbutyl. 25. a. Predict the product of electrolysis in the following: i. An aqueous solution of silver nitrate with siver electrodes ii. A dilute solution of sulphuric acid with platinum electrodes iii. An aqueous solution of CuCl 2 with platinum electrodes. b. The resistance of a conductivity cell containing M KCl solution at 298 K is 1500 ohm. What is the cell constant if the conductivity of M KCl solution at 298 K is x 10-3 S/cm 26 a. Assign a reason for each of the following statement: i. Anhydrous AlCl 3 acts as a catalyst in many organic reaction ii. All the bonds in a molecule of PCl 5 are not equal ix. Hydrogen Fluoride is a weaker acid than hydrogen chloride in aquoeous solution b. Write structure for the following: i. IF 5 ii. XeOF 2 Or// a. Assign a reason for the following statements: iv. SF 6 is easily hydrolysed.

12 v. In solid PCl 5 exists as an ionic compound vi. CO 2 and SiO 2 are not isostructural. b. Arrange the following in the decreasing order of the property indicated ii. H 2 O, H 2 S, H 2 Se, H 2 Te -- boiling point iii. F,Cl, Br, and I --- Bond energy 27 a. Give reason: i. Many thermodynaically feasible reactions do not occur under ordinary condition. ii. An exothermic reaction is sometimes not spontaneous. b. The standard Gibbs energy Change values at 1773 K are given for the following reactions: 4 Fe + 3 O 2 2Fe 2 O 3 G = Kj/mole 4 Al + 3 O 2 2 Al 2 O 3 G = Kj/mole 2 CO + O 2 2CO 2 G= -515Kj/mole Find out the possibility of reducing Fe 2 O 3 and Al 2 O 3 with CO at this temperature.

CHEMISTRY 2005 (Delhi) Q1. What is the maximum possible coordination number of an atom in an hcp crystal structure of an element?

CHEMISTRY 2005 (Delhi) Q1. What is the maximum possible coordination number of an atom in an hcp crystal structure of an element? General Instructions: 1. All questions are compulsory. 2. Marks for each question are indicated against it. 3. Question numbers 1 to 5 are very short-answer questions, carrying 1 mark each. Answer these