Cbse Chemistry Sample Question Paper

CBS E C hemi str y S am ple Que stion P aper - Yea r 2000 Filed under: • •

Class XII Chemistry Chemis tr y C las s - XII (CB SE ) You ar e on Se t 1 ques tions 1 to 20

Q.1 What is the physical significance of the lines in the following depiction of atomic orbitals? (Ma r k 1) Q.2 An ionic compound AB2 possesses CaF2 type crystal structure. Write the coordination numbers of A2+ and B- ions in the crystals of AB2. (AB2+ = 8, B- = 4 ) (Ma r k 1) Q.3 How many state of a thermodynamic system be defined? (Ma r k 1) Q.4 State Kohlrausch’s law for electric conductance of an electrolyte at infinite dilution. (Mar k 1) Q.5 For the reaction 3N2 (g) + H2 (g) —-> 2NH3 (g), how are the rate of reaction expression -d[H2]/ dt and d[NH3]/dt interrelated? (Ma r k 1) Q.6 Mention the use of fromalin in industry.

(Mar k 1) Q.7 For an amine RNH2 write the expression for Kb to indicate its base strength. ( Mar ks 1) Q.8 What is responsible for the blue colour of a solution of an alkali metal in liquid ammonia? (Mar k 1) Q.9 Why do colloidal solution exhibit Tyndall effect? (Ma r k 1) Q.10 Write any one characteristics feature of enzymatic catalysts. (Mar k 1) Q.11 Account for the following : (i) Silicon is an insulator but silicon doped with phosphorous acts as a semiconductor. (ii) Some of the glass objects recovered from ancient monuments look milky instead of being transparent. (Mar k 2 ) Q.12 Give an example each of miscible liquid pairs showing positive and negative deviation from Raoult’s law. Give one reason each for deviation. ( Mar k 2) Q.13 Starting with thermodynamic relationship E = q - P V and H =E + PV derive the relationship H = qp (Mar k 2 ) Q.14 From the data given below at 298 K for the reaction :

CH4 (g) + 2O2 (g) ——> CO2 (g) + 2H2O (l) Calculate the enthalpy of formation of CH4 (g) at 298 K. Enthalpy of reaction = - 890.5 kJ Enthalpy of formation of CO2 (g) = - 393.5 kJ mol-1 Enthalpy of formation of H2O (l) = - 286.0 kJ mol-1 (Ma r k 2) Q.15 Give the IUPAC names of : Ima ge no .1 (Mar k 2 ) Q.16 Give explanation for the following observation : (i) An ether would possess a dipole moment even if the alkyl groups present in it are identical. (ii) Towards nucleophilic reagents aldehydes are more reactive tan ketones. (Ma r k 2) Q.17 For the following conversion reaction write the chemical equations : (i) Ethyl isocyanide to ethylamine (ii) Aniline to N-phenylthanamide(Mar k 2 ) Q.18 Account for the following : (i) Ammonolysis of alkylhalides does not give a corresponding amine in pure state. (ii) If -NO2 or -COOH groups is attached to a carbon of benzene ring, electrophilic substitution becomes difficult. ( Mar ks 2 )

Q.19 The sum of first and second ionisation energies and those of third and fourth ionisation energies of nickel and platinum are given below :

Ni Pt

I E + IE2(MJ mol1 )

I E3 + IE4(MJ mol-1)

2.49

8.80

2.66

6.70

alues into account write : (i) The most common oxidation state are for Ni and Pt and its reason. (ii) The name of metal (Ni and Pt) which can form compound in +4 oxidation more easily and why. ( Mar ks 1) Q.2 0 (i) Of the ions Ag+, Co2+ and Ti+, which ones will be coloured in aqueous solution (Atomic numbers : Ag = 47, Co = 27, Ti = 22) (ii) If each one of the above ionic species is in turn place in a magnetic field, How will ir respond and why? (Ma r ks 2) Q.21 Among ionic species, Sc3+, Ce2+ and Ti4+, which ones will be occurred in aqueous solution? (Atomic number : Sc = 21, Ce = 58, Eu = 63) (Mar ks 2 ) Q.2 2 Explain the following processes with a suitable example in each case :

(i) Chain - growth polymerisation (ii) Step - growth polymerisation (Mar ks 2 ) Q.2 3 Given an example of each, differentiate between multi-molecular and macromolecular colloides. ( Mar ks 2 ) Q.2 4 What are polysaccharides? Name one of the. How is it important for us. (Ma r ks 2) Q.25 What do you understand by the statement : “ATP molecules are the currency of energy metabolism in a cell.” (Ma r k 2) Q.26 Name the broad spectrum antibiotic and state two diseases for which it is prescribed. (Ma r k 2) Q.27 The ionisation energy of hydrogen atom in ground state is 1312 kJ mol-1. Calculate the wavelength of radiation emitted when the electron in this atom makes a transition from n = 2 state to n = 1. (Planks constant, h = 6.63 x 10-34 Js, velocity of light = 3 x 1010 cm s-1 and Avogadro number, NA = 6.02 x 1023 mol-1) ( Mar ks 3 ) Q.2 8 On dissolving 3.24g of sulphur in 4.0g of benzene boiling point of solution was higher than that of benzene by 0.81 K. Kb value for benzene is 2.53 K kg mol-1. What is the molecular formula of sulphur ? (Atomic mass of sulphur = 32 g mol-1) (Ma r ks 3)

Q.29 Calculate the cell emf and Ima ge n o.3 G for the cell reaction at 25oC for the cell Zn (s) | Zn2 + (0.0004 M) || Cd2+ (0.2 M) | Cd (s) Eo values at 25o C : Zn2+ / Zn = - 0.763 V ; Cd2+/ Cd = -0.403 V; F = 96500 C mol-1; R = 8.314 JK -1. ( Mar ks 3 ) Q.3 0 Describe how important functions each of the elements P, B and S in green plants and also write the deficiency symptoms of any two of them. (Ma r ks 3) Q.31 Describe the following : (i) Optical isomerism. (ii) Magnetic behaviour of [Ni(CN)4]2- ion. (At. No. of Ni =28) (iii) Preparation of tetrabutyl tin (Ma r ks 3) Q.3 2 (i) What is nuclear fission reaction (ii) Describe the basic principle of a nuclear reactor? (Ma r ks 3, 2) Q.3 3 (a) Write chemical equation and reaction conditions for the conversion of : (i) Propane to 1-bromo-propane (ii) Chlorobenzene to phenol (iii) 2-propanol to iodoform (b) How is glycerol obtained commercially, state its two uses. (Ma r k 3) Q.3 4 (a) Account for the following observation : (i) In several chemical properties lithium

resembles magnesium. (ii) +1 oxidation state of thallium (atomic no 81) is more stable than its +3 oxidation state. (iii) Boron chloride exists as a monomer while in the same group anhydrous aluminium chloride exists as adimer. (b) Complete and balance the following chemical equation : (i) NH3 + NaOCl —-> (ii) XeF4 + SbF5 (Ma r k 3, 2 ) CBS E C hemi str y S am ple Que stion P aper - Yea r 1999 Filed under: • •

Class XII Chemistry

Chemis tr y C las s - XII (CB SE ) You ar e on qu es tions 1 t o 2 0 of Se t I Q.1 Define an atomic orbital. What does angular momentum quantum number tell about an orbital ? (1 m ar k) Q.2 Which one of the two, O-2 or O 2-2 has higher bond order and why?(1 m ar k) Q.3 Define dislocation in crystal. (1 ma r k) Q.4 Write an example of neutral molecule which is isoelectronic to CIO-.

(1 ma r k) Q.5 Express the relationship between degree of dissociation of an electrolyte and its molar. Conductivity. (1 m ar k) Q.6 What for are quaternary ammonium salts widely used? (1 ma r k) Q.7 What is meant by Faraday constant? (1 mar k) Q.8 Define the “Ligand". Give an example also. (1 ma r k) Q.9 Give an example of the compound in which hydrogen bonding results in the formation of adimer. (1 m ar k) Q.10 Write an general formula by which the electronic configurations of the transitions element is represented. (1 ma r k) Q.11 Calculate the uncertainty in the position of an electron if the uncertainty in its velocity is 5.7 x 105 ms-1. (h = 6.6 x 10-34 Js and mass of electron = 9.1 x 10-31kg) (1 mar k) Q.12 (i) What is the basic building unit of silicates? (ii) Draw the structure of asbestos (a silicate containing SiO2-3 anions).(2 m ar ks)

Q.13 State Rault’s law. Discuss the factors responsible for the deviation from this low. (2 mar ks) Q.14 Calculate the molarity and molality of a 15% solution (by weight) of sulphuric acid of density 1.020 g cm-3. (Atomic masses : H = 1, O = 16, S = 32 amu) (2 m ar ks) Q.15 Derive the following equation : (2 mar ks) D H = DE + ( Dn) RT Q.16 A first order reaction is 15% complete in 20 minutes. How long will it take to be 60% complete. ( 2 ma r ks) Q.17 Calculate the potential of a zinc-zinc ion electrode in which the zinc ion activity is 0.001 M. (EoZn2+/Zn. = – 0.76 V, R = 8.314 JK-1 mol-1, F = 96,500 mol-1) (2 m ar ks ) Q.18 Nitric oxide reacts with hydrogen to give nitrogen and water. 2 NO + 2 H2 –> N2 + 2 H2O The kinetics of this reaction is explained by the following steps : (i) 2 NO + 2 H2 –> N2 + 2 H2O (slow) (ii) H2O2 + H2 –> 2 H2O (fast) What is the predicted rate low ? (2 m ar ks )

Q.19 Write the IUPAC names of the following compounds.

(i) (ii)

Q.20 Write the reaction involved in the preparation of benzene daizonium chloride. What happens when benzene daizonium chloride reacts with (i) Cu2Cl2 and (ii) phenol ?(Given equation for the reaction) (2 m ar ks )

Q.21 Account for the following : (2 m ar ks ) (i) Alkylamines are stronger bases than arylamines. (ii) Toluene is more easily nitrated than benzene.

Q.22 (i) Why do the transitional metals slow variability in their oxidation state? (ii) Write formula of a compound where the transitional metal is in +7 oxidation state. (2 m ar ks )

Q.23 Draw the structure and write the hybridisation state of the central atom of each of the following species : (i) Fe(CO)5 (ii) trans-[CO(NH3)4Cl2]

+

(Atomic Number : Fe = 26, CO = 27) (2 m ar ks )

Q.2 4 What happens during glycolysis and what are the products of glycolysis ? (2 ma r ks)

Q.25 What are antibiotics? Name any two antibiotics which are specific for certain diseases. (2 marks)

Q.26 How are Buna-S and Terylene synthesised? Give chemical equations.(2 mar ks )

Q.27 When 0.532 g of benzene (C6H6), boiling point of 353 K, is burnt with excess of oxygen in a constant volume system, 22.3 kJ of heat is given out. Calculate H for the combustion process. (R=8.31 J K-1 mol-1) (3 ma r ks)

Q.28 Account for the following : (i) Of the lanthanide’s, cerium (atomic number 58) forms tetrapositive ion, Ce4+ in aqueous solutions. (ii) Transition metals have high enthalpy of atomisation. (iii) Scandium forms no coloured ions and yet it is regarded as a transition element. (3 m ar ks )

Q.29 Explain giving reason for each of the following : (i) Chloroaceticacid has higher pKa value than acetic acid. (ii) Carboxylic acid have higher boiling points than the alcohol’s of comparable molecular masses. (iii) Electrophilic substitution in benzoic acid takes places at meta position.(3 mar ks )

Q.30 (i) Explain the meaning of the statement, “Absorption is a surface phenomenon.” (ii) State two features of chemical adsorption which are not found with physical adsorption. ( 3 ma r ks)

Q.31 (i) What is photosynthesis? Where does it occur in plants? (ii) Name two products of photosynthesis which are required for the survival of most of the chemotrophs. (3 m ar ks )

Q.32 Complete the following nuclear reactions : 96 97 (i) 42Mo(…..,n) 43Tc 211 (ii) ……….( , 2n) 85At 246 12 1 (iii) 96 + 6 –> …… + 4( 0n) (3 m ar ks )

Q.33 (a) Account for the following : (i) Haloalkanes are more reactive than haloarenes. (ii) Phenols are acidic in nature. (iii) Unlike phenols, alcohol’s are easily protonated. (b) Write the reactions involved in the preparation of :

(i) 1, 2-ethanediol from ethene, and (ii) iodoform from 2-propanol (5 m ar ks )

Q.3 4 Present a comparative account of the following : (i) Physical states of nitrogen and phosphorus. (ii) Maximum covalency numbers of oxygen and sulphur. (iii) Bond energies of F2 and Cl2. (iv) Structures of chlorides of boron and aluminium. (v) Proton affinities of NH3 and PH3 (5 m ar ks )

CBS E C hemi str y S am ple Que stion P aper - Yea r 1998 Filed under: • •

Class XII Chemistry Chemis tr y C las s - XII (CB SE ) You ar e on Set no 1 Q.No . 1 to 20

Time allowed : 3 hours Maximum Marks : 70 Gene r al Ins tr uction s : (i) All questions are compulsory. (ii) Marks for each question are indicated against it. (iii) Question number 1 to 10 are very shortanswer questions each of 1 mark. Answer them in about one sentence each. (iv) Question number 11 to 26 are shortanswer questions of 2 marks. Answer them in

not more than 30 words each. (v) Question number 27 to 32 are shortanswer questions of 3 marks. Answer them in not more than 40 words each. (vi) Question number 33 to 34 are longanswer questions of 5 marks each. Answer them in not more than 70 words each. (vii) Use Log tables, if necessary. (viii) Please write down the serial number of the question before attempting it. Q1) Write the MO electronic configuration of a diatomic molecule having a bond order of three ? (Ma r ks 1) Q2) What are non-stoichiometric compounds ? (Mar ks 1) Q3) Complete the nuclear reaction expression ? (Ma r ks 1) 20

Co59 (d,p)……

Q4) Write the IUPAC name of (Ma r ks 1) Image no.1 Q5 ) Why do noble gases form compounds with fluorine and oxygen only ? (Mar ks 1) Q6 ) Why is hydrochloric acid not used to acidify a permanganate solution in volumetric estimations of Fe2+ or C2O42-? (Ma r ks 1)

Q7 ) How many isomers are there for the complex [Co(NH3)4 Cl2]Cl? (Mar ks 1) Q8) Why are carbohydrates generally optically active? (Mar ks 1) Q9 ) Give one important use of each of the following in pharmacy : (Ma r ks 1) (i) Equanil (ii) Morphine Q10) Illustrate the function of mordent’s by one example. ( Mar ks 1) Q1 1) Predict the structure of MgO crystal and co-ordination number of its cation in which the cation and anion radii are equal to 65 pm and 140 pm respectively. (Mar ks 2 ) Q12) With the help of suitable diagrams, illustrate the two types of non-ideal solutions. (Mar ks 2 ) Q13) What is meant by average bond energy? In what way is it different from bond energy of a diatomic molecule ? Give suitable examples. (Mar ks 2 ) Q14) Explain Kohlrausch’s law of independent migration of ions. Mention one application of Kohlrausch’s law. (Mar ks 2 ) Q1 5) For what concentration of Ag+ (aq) will the e.m.f. of the given cell be zero at 25oC, if

concentration of Cu2+ (aq) is 0.1 M? (Mar ks 2) CU (s) | Cu2+ (0.1 M) || Ag+ (aq) | Ag (s) [ Given Eo Ag+/Ag = + 0.80 V; Eo Cu2+/Cu = + 0.34 V ] Q1 6) (a) Show graphically how the rate of a first order reaction with only one reactant depends upon the concentration of the reactant. (b) Give one example of a first order reaction. (Mar ks 2 ) Q1 7) For a reaction, the energy of activation is zero. What is the value of rate constant at 300 K, if k = 1.6 x 106 s-1 at 280 K ? [ R = 8.31 JK-1 mol-3 ] (Mar ks 2 ) Q18) 1.0 x 10-6 g of radioactive iodine is injected into the blood of a patient. How long will it take for radioactivity to fall to 10% of the initial value? [ Given t1/2 for 53I133 = 8.05 days ] (Ma r ks 2) Q1 9) Account for the following : (i) Formaldehyde gives Cannizaro’s reaction whereas acetaldehyde does not. (ii) Carboxylic acids do not give the characteristic reactions of carbonyl group. (Mar ks 2 ) Q20 ) How are the following conversions carried out?

(i) Ethanoic acid to propanoic acid. (ii) Ethanol to propanone. Write reaction equations and conditions to support your answer. (Mar ks 2 ) Q21) Give an example of each with necessary reaction conditions : (i) Sandmeyer’s reaction (ii) Kharasch Effect (Ma r ks 2) Q22 ) What is ‘inert pair effect’? Discuss the oxidation states of Group 13 elements in relation to this effect. (Ma r ks 2) Q23 ) A co-ordination compound has the formula CoCl3.4NH3. It does not liberate ammonia but precipitates chloride ions as silver chloride. Give the IUPAC name of the complex and write its structure formula. (Mar ks 2 ) Q24 ) Write the information asked for in the following polymers : (i) Bakelite : material used for preparation (ii) Synthetic rubber : monomer unit (iii) PVC : monomer unit (iv) Nylon-66 : materials required for preparation. (Mar ks 1) Q25) “The two strands of DNA are not identical but are complementary.” Explain this statement. ( Mar ks 2 )

Q26) Write the structure of adenosine triphosphate indicating clearly the energy rich bonds. How does this molecule form the source of energy? (Ma r ks 2) Q27) Explain how an electron can be considered to have a particle as well as nature. A moving electron has 4.9 x 10-25 joules of kinetic energy. Find out its De Broglie wavelength. (Given h = 6.6x10-34 Js; m = 9.1x10-31 kg) (Mar ks 3 ) Q28 ) An aqueous solution freezes at 272.4 k, while pure water freezes at 273.0 K. Determine : (i) the molality of the solution, (ii) boiling point of the solution, (iii) lowering of vapour pressure of water at 298K. [ Given Kf = 1.86 K kg mol-, Kb = 0.512 K kg mol-1 and vapour pressure of water at 298 K = 23.756 mm Hg ] (Mar ks 3)

Q29 ) (a) When NH NO (s) decomposes at 373 K, it forms N (g) and H O(g). 4 2 2 2 The H for the reaction at one atmosphere pressure and 373k is -223.6 kJ mol-1 of NH NO (s) decomposed. What is the value of E for the reaction under the 4 4 same conditions? [ Given R = 8.31 JK- mol-1 ] (b) Account for the fact that E is numerically bigger H in the above case. (Mar ks 3)

Q30) What is meant by the colloidal state of matter? Explain the following terms :

(i) Multi-molecular colloids (ii) Elector-dialysis (Ma r ks 3 )

Q31 ) An organic compound A having molecular formula, C H O give a 6 6 characteristic colour with aqueous FeCl solution. A on treatment with CO 3 2 and NaOH at 400 K under pressure gives B which on acidification gives a compund C. C reacts with acetyl chloride to give D which is a popular painkiller. Deduce the structures of A, B, C and D (Ma r ks 3 )

Q32 ) (a) Write the balanced equations for the following reactions : 450 K (i) BF3 + LiH (ii) NH3 + NaOCl (iii) SiCl4 + H2O (iv) XeF6 + KF (b) State the reason for the occurrence of “diagonal relationship” in the periodic table. ( Ma r ks 3)

Q33 ) (a) Write the general formula for nitroalkanes and for alkyl nitrites. (b) How are nitroalkanes prepared alkanes? © What happens when : (i) nitroethane is treated with lithium aluminium hydride, (ii) nitrobenzene is reduced with hydrogen using copper oxide as catalyst. (d) Write two use of nitroalkanes, one each in the laboratory and in the industry. (Mar ks 5)

Q34) (a) (i) What are inner transition elements? Write their general electronic configuration. (ii) In what way are the observed oxidation states of the lanthanide’s related to their electronic configuration? (b) Describe the general characteristics of the transition elements with special reference to their tendency to : (i) exhibit paramagnetism,

(ii) form complex compounds, (iii) their catalytic behaviour. (Mar ks 5)

CBS E C hemi str y S am ple Que stion P aper - Yea r 199 7 Filed under: • •

Class XII Chemistry

Chemis tr y C las s - XII (CB SE ) You ar e on qu es tions 1 t o 2 0 of Se t I Q.1 State the physical significance of 2. (1 mar k) Q.2 Write which one out of O+2 and O–2 is more stable? (1 m ar k) Q.3 Write an expression in the form of a chemical equation for standard enthalpy of formation of for CO? (1 m ar k) Q.4 Write an expression to relate molar conductivity of an electrotype to its degree of dissociation? (1 m ar k) Q.5 What is the ‘ambident group’ ? Give an example. (1 m ar k) Q.6 Indicate a chemical reaction involving a homogeneous catalyst ? (1 m ar k) Q.7 Mention two main function of

carbohydrates in plants ? (1 ma r k) Q.8 How many sigma bonds are present in 3methylphenol ?(1 m ar k) Q.9 Mention the chief reason for the resemblance between beryllium and aluminium ? (1 ma r k) Q.10 Mention two important uses of sulphuric acid ? (1 ma r k) Q.11 What is energetically achieved by coupling reaction in biological system? Explain. (1 ma r k) Q.12 What types of substance generally constitute a chemical propellant? Briefly describe the function of rocket propellant. (2 mar ks) Q.13 The ionisation energy of hydrogen atom is 1.312x106 J mol-1. Calculate the energy required to excite the electron in a hydrogen atom from the ground state to the first excited state. (Avagadro constant=6.022x1023 mol-1)(2 m ar ks) Q.14 Describe briefly two important function of nucleic acid. ( 2 ma r ks) Q.15 Calculate the free energy change when one mole of sodium chloride is dissolve in water at 298K.

(Given : Lattice energy of NaCl= -777.8 kj mol-1, Hydration energy of NaCl= -774.1kj mol-1 and S at 298 K = 0.043 K-1mol-1. (1 mar k) Q.16 For the equilibrium PCl5(g) < ===> PCl5(g) + Cl2(g) at 298 K, K=1.8x10-7. Calculate Go for the reaction. (R=8.314JK-1mol-1). (1 ma r k) Q.17 The freezing point of pure nitrobenzene is 278.8 K. When 2.5gm of an unknown substance is dissolve in 100gm of nitrobenzene, the freezing point of the solution is found to be 276.8K. If the freezing point depression constant of nitrobenzene is 8.0K Kg mol-1, what is the molar mass of unknown substance? ( 2 ma r ks) Q.18 For the reaction, 2A+2B+C—–> A2B+C, rate law has been determined to be: rate = k[A][B]2. If the rate constant, k = 2.0x10-6 mol6 2 L and [C]=0.8 mol L-1? (2 marks) Q.19 For the reaction NO2(g)+ CO(g)—–>CO2(g) + NO(g) the approximately determined rate expression below 400K is rate = k[NO]2 what mechanism can be proposed for above reaction. (2 m ar ks) Q.2 0 write IUPAC name of the following compounds : (i) (CH3)3C.CH2.CH2Cl

(ii) CH3.CH.CH.CH.CHO (2 ma r ks ) Q.21 Explain the mechanism of the acidcatalysed dehydration of ethanol at high temperature. ( 2 ma r ks) Q.2 2 Comment on the structural difference between thermoplastics and thermosetting polymers. (2 ma r ks ) Q.2 3 What are micels? Given an example of a micellar system. (2 ma r ks ) Q.2 4 Consider the given standard potentials (in volts)in 1 M acidic solution : Fe2+/Fe, -0.4 V ; Fe3+/Fe2+, +0.8 V Mn2+/Mn, -1.2 V ; Mn3+/Mn2+, +1.5 V (i) Comment on the relative stabilities of +2 and +3 oxidation states of iron and manganese; (ii) Which of the two metals may be more easily oxidised to +2 state?(2 m ar ks) Q.25 Account for the following statements : (2 ma r ks ) (i) Co(II) is stable in aqueous solution but in the presence of strong ligands and air it can get oxidised to Co(III). (Atomic number Co=27) (ii) One among the lanthanide’s,Ce(III) can be easily oxidised to Ce(IV). (Atomic No : Ce=58).

Q.26 Write an equation in ionic form to represent the oxidising action of Cr2O2-7 in acidic medium. Also draw the structure of Cr2O2-7. (2 m ar ks) Q.27 An element of atomic mass 98.5g mol-1 occurs in fcc structure. If its unit cell edge length is 500pm and its density is 5.22g cm-3, what is the value of Avagadro Constant? (3 mar ks) Q.2 8 One litre aqueous solution of sucrose (molar mass=342g mol-1) weighing 1015g is found to record an osmotic pressure of 4.82 atom at 293k. What is the molarity of the sucrose solution? (R=0.0821 atom mol-1K-1)(3 mar ks) Q.29 Calculate the potential of the following cell reaction at 298K : Sn4+(1.50M) + Zn(s) —> Sn2+(0.50M) + Zn2+(2.0M) The standard potential Eo of the cell is 0.89 V. Whether the potential of the cell will increase or decrease, if the concentration of Sn4+ is increased in the cell? (R = 8.314JK-1 mol-1; F=96,500 C mol-1) (3 ma r ks ) Q.3 0 (a) How many b -particles are emitted in the decay series : 238 U92 —> 206 Pb82 ? (b) Complete the following nuclear reaction : (i)2713 Al + 42 H –> 3015 Pb + …..

(ii)23592 U +

1

0

n –>

140

56

+…..+ 210n (3 m ar ks)

Q.31 How are the following conversions accomplished? (Write reaction only) (i) Aniline to Chloro-benzine (ii) Nitrobenzene to phenol (iii) Aniline to benzoic acid (3 ma r ks ) Q.3 2 Select the complex formation reaction and write an expression for the stability constant of the complex species. What information is conveyed regarding the strength of ligands from the stability constant values of their complexes with a metal ion? Illustrate your answer with example of monodentic ligands. (3 ma r ks ) Q.3 3 (a) Explain giving reason each of he following : (i) CCl4 remains unaffected whereas SiCl4 is easily hydrolysed by water. (ii) Nitrogen exists as a diatomic molecule, N2, whereas phosphorus exists as tetraatomic molecule, P4. (iii) SF6 is known but SH6 not known. (b) Write the balance equation fro the following reaction : (i) B2H6 + LiH —> (ii) BrO3 + F2 + OH—-> (5 m ar ks ) Q.3 4 (a)You are provided with 4 reagent : LiAlH4, I2/NaOH, NaHSO3 and Sciff’s reagent. Write which two reagents can be used to

distinguish between the compounds in each of the following pairs : (i) CH3CHO and CH3COCH3 (ii) CH3CHO and C6H5CHO (iii) C6H5COCH3 and C6H5COCH3 and C6H5COC6H5 (b) Account for the following : (i) The order of reactivity of halogen acids with ether is HI > HBr > HCl (ii) The pKa value of choloroacetic acid is lower than the pKa value of acetic acid. (5 mar ks)