Chemistry-7.Work Book (Phase - VII)

Work Book (Phase - VII) Subjective: Board Type Questions 1. A sample of lead weighing 1.05 g was dissolved in a small quantity of nitric acid to produce aqueous solution of Pb2+ and Ag+ (which is present as impurity). The volume of the solution was increased to 300 ml by adding water, a pure silver electrode was immersed in the solution and the potential difference between this electrode and a standard hydrogen electrode was found to be 0.503 V at 25°C. What was the % of Ag in the lead metal? Given =0.799 V. Neglect amount of Ag+ converted to Ag. 2. Specific conductance of a decinormal solution of KCl is 0.0224 . The resistance of a cell containing the solution was found to be 64. What is the cell constant? 3. Calculate the electrode potential of a copper electrode dipped in a 0.1 M solution of copper sulphate at the standard electrode potential of system is 0.34 volts at 298 K. 4. Given: I. II. Find E0 for the half reaction: 5. NaOH prepared by the electrolysis of NaCl(aq). If current efficiency is 80% then determine the quantity of electricity required to convert 20g NaCl in NaOH 6. Iron is corroded by atmospheric oxygen under acidic condition to product Fe2+ (aq) ions initially. The standard reduction potential E0Fe2+/Fe = -0.44 V and for the reaction H¬2O ( ) ¾® 2H+ (g) + E0 = -1.23 V Find whether the formation of Fe2+ (aq) is thermodynamically favorable or not. 7. The emf of the cell reaction, Calculate the entropy change. Given that enthalpy of the reaction is - 216.7 KJ mol-1 And and = + 0.34V. 8. Arrange HCl, LiCl, NaCl, KCl and RbCl in order of increasing value in aqueous solution. 9. (a) AlCl¬3 is covalent but AlCl3×6H2O is ionic. Why? (b) Explain why BaSO4 is insoluble in water through it is basic. 10. What happens when aluminium forms [AlF6]3– but boron does not form [BF6]3–. 11. What happens when? Methyl chloride is passed over silicon in the presence of copper catalyst at 275 - 375°C. 12. Why ‘Al’ extraction from Bauxite is not possible by carbon reduction method? 13. Identify (A) based on following facts: (i) (A) reduces HgCl2 solution to white ppt. changing to grey. (ii) (A) turns FeCl3 yellow colour solution to green. (iii) (A) give white ppt. with NaOH soluble in excess of NH4OH (iv) (A) gives yellow dirty ppt. on passing H2S gas soluble in yellow ammonium sulphide. (v) A gives chromyl chloride test. 14. Give reason why the hydroxides of aluminium and iron are insoluble in water. However, NaOH is used to separate one from the other? 15. In the reaction H2+I2 ¾® 2HI the rate of disappearance of I2 is found to be 10-6 mole per litre per second. What would be the corresponding rate of appearance of HI? 16. Rate of reaction A + B ¾® product is given as a function of different initial concentration of A and B Determine the order of reaction with respect to A and with respect to B. What is the value of rate constant? A (mole L-1) (B) (mole L-1) Initial rate (mole L-1 min-1) 0.01 0.02 0.01 0.01 0.01 0.02 0.005 0.010 0.005 17. For the formation of phosgene from CO(g) and CO(g) + Cl2(g) ¾® COCl2(g), The experimentally determined rate law is, K¢[CO] [Cl2]3/2, is the following mechanism consistent with the equation? (i) Cl2 2Cl (fast) (ii) Cl + CO COCl (fast) (iii) COCl + Cl2 COCl2 +Cl(slow) 18. A first order reaction have rate constant of 1.5´10-4 sec-1. How long will 5.0 gm of this reactant take to reduce to 3.0 gm? 19. In the Arrhenius’ equation for a certain reaction, the value of A and Ea are 4´1013 sec-1 and 98.6 KJ mol-1 respectively. If the reaction is of first order at what temperature will its half life period be ten minutes? 20. The gas phase decomposition 2N2O5 ¾® 4NO2+O2 follows the first orde rate law. At given temperature rate constant of the reaction is 7.5´10-3 sec-1. The initial pressure of N2O5 is 0.1mol-1. Calculate the time of decomposition of N2O5 so that the total pressure becomes 0.15 atm 21. Calculate the number of a and b particles emitted when 92U238 changes into radioactive 82Pb206 22. A radioisotope has t1/2 = 5 years. After a given amount of decays for 15 years, what fraction of the original isotope remains? 23. The half life period of is 140 days. In how many days 1 gm of this isotope is reduced to 0.25 gm? 24. From the following data for the reaction between A and B Expt. (A) (B) Initial rate at (mol L-1) (mol L-1) 300 K (i) 2.5´10-4 3.0´10-5 5.0´10-4 (ii) 5.0´10-4 6.0´10-5 4.0´10-3 (iii) 1.0´10-3 6.0´10-3 1.6´10-2 (i) Calculate the order of the reaction with respect to A and B (ii) Rate constant of the reaction at 300 K 25. A substance reacts according to I order Kinetics and rate constant for the reaction is 1´10-2 sec-1. If its initial concentration is 1 M (a) What is initial rate? (b) What is rate after 1 minute? 26. The beta activity of 1 gm of carbon made from green wood is 15.3 counts per minutes. If the activity of 1 gm of carbon derived form the wood of an Egyptian mummy ease in 9.4 counts per minutes under the same conditions, how old is the wood of the mummy case (t1/2 of C14 = 5770 gm) 27. Differentiate between: (a) Artificial transmutation and nuclear fission. (b) Nuclear fission and nuclear fusion. (c) Chemical reaction and nuclear reaction. 28. Define rate of a reaction. 29. For the hypothetical reaction: write the rate equation in term of the disappearance of B2 and formation of AB2. 30. In the reaction Express the rate of disappearance of Br in terms of formation of Br2. 31. Define specific rate constant. 32. For the reaction , the rate constant is 1.26  103 L mol1s1. What is the order of the reaction? 33. The gas – phase decomposition of acetaldehyde. follows the rate law If pressure is in atmosphere and the time is in minutes. Find the units for (i) rate of reaction (ii) rate constant. 34. The rate law for the reaction Which is the order of a reaction in the absence of HBr? 35. Give any one example of (i) zero order reaction (ii) first order reaction 36. Write the integrated rate equation for a zero order reaction. 37. For the decomposition of NH3 on a finely divided Pt surface is represented as with the rate equation Write the rate equation and order of a reaction when (i) [NH3] is very slow. (ii) [NH3] concentration is very high. 38. The following graph is a plot of the rate of reaction versus concentration of the reactant. What is the order of the reaction? 39. Define half-life of a reaction. 40. The following graph is a plot of t1/2 and concentration. What is the order of the reaction? IIT Level Questions 41. A hydrogenation reaction is carried at 500 K. If the same reaction is carried in presence of catalyst at the same rate the temperature required is 400 K. Calculate the activation energy of the reaction if the catalyst lowers the activation energy by 20 KJ mol-1 42. A radioisotope = Am(t1/2=10days) decays to give Bm-12 (stable atom) along with a - particles. If m gm of A are taken and kept in a sealed tube how much ‘He’ will accumulate in 20 days at STP? 43. A small amount of solution containing Na24 radionuclide with activity A = 2´103 dps was administered into blood of a patient in hospital, after five hour sample of blood drown from the patient showed activity of 16 dpm per cc. Find the volume of the blood in the patient . (t1/2Na24), 15 hr 44. The EMF of the cell Pt |H¬2 (1 atm), HA (0.1 M, 30 ml) || Ag+ (0.8 M) | Ag is 0.9V. Calculate the EMF when 0.05 M NaOH (40 ml) is added.( ,antilog of 2.2 = 6.3´10-3, log 2 = 0.3010, log 2.5 = 0.3979, log 1.56 = 0.194) [6] 45. Find the solubility product of a saturated solution of Ag2CrO4 in water at 298K if the emf of the cell: Ag | Ag+ (sat Ag2CrO4 solution) || Ag+ (0.1 M) | Ag is 0.164 at 298K 46. An inorganic compound (A) shows the following reaction. (i) It is white solid and exists as dimer; gives fumes of (B) with wet air. (ii) It sublimes in 180°C and form monomer if heated to 400°C. (iii) Its aqueous solution turns blue litmus to red. (iv) Addition of NH4OH and NaOH separately to a solution of (A) gives white ppt. which is however soluble in excess of NaOH. 47. Why we prefer instantaneous rate of reaction over average rate of reaction? 48. Differentiate between the rate of reaction and the rate constant. 49. Define order of a reaction. Can it be a fractional value? If yes then give an example of a fractional order reaction. 50. A first order reaction is 60 percent complete in 100 minutes. Find the time when 90 percent of the reaction will be completed. Objective: Multiple choice questions with single correct options 1. If in the fermentation of sugar in an enzymatic solution that is 0.12 M, the concentration of the sugar is reduced to 0.06 M in 10 h and to 0.03 M in 20 h, what is the order of the reaction (A) 1 (B) 2 (C) 3 (D) 0 2. For gaseous reactions, the rate is often expressed in terms of dP/dt instead of dC/dt or dn/dt (where C is concentration and n the number of mol). What is relation among these three expressions? (A) (B) (C) (D) None is correct 3. Milk turns sour at 40oC three times as faster at as 0oC. Hence E in cal (activation energy) of turning of milk sour is: (A) (B) (C) (D) 4. For the reaction net rate is ratio of rate constants of the forward and backward reactions is (A) 0.66  109 mol L1 (B) 1.5  109 mol L1 (C) 2.0  104 s1 (D) 3.0  105 L mol1 s1 5. A G.M. counter is used to study the radioactive process. In the absence of radioactive substance A, it counts 3 disintegration per second (dps). At the start in the presence of A, it records 23 dps; and after 10 minutes 13 dps, (1) What does it count after 20 minutes? (2) What is half-life of A? (a) 8 dps, 10 min (B) 5 dps, 10 min (C) 5 dps, 20 min (D) 5 dps, 5 min 6. Rate of formation of SO3 in the following reaction is 100 kg min1. Hence rate of disappearance of SO2 will be (A) 100 kg min1 (B) 80 kg min1 (C) 64 kg min1 (D) 32 kg min1 7. Following is the graph between (a  x)1 and time t for second order reaction  = tan1(0.5) OA = 2 L mol1 hence rate at the start of the reaction is (A) 1.25 L mol1min1 (B) 0.5 mol L1 min1 (C) 0.125 L mol1 min1 (D) 1.25 L mol1 min1 8. Temperature T/K at which (kA = kC) is (A) 1000 K (B) 2000 K (C) (D) 9. Reaction kinetics can be studied by (A) measurement of pH (B) titration with hypo after adding KI (C) both correct (D) none is correct 10. The rate of a chemical reaction generally increases rapidly even for small temperature increase because of a rapid increase in the (A) collision frequency (B) fraction of molecules with energies in excess of the activation energy (C) activation energy (D) average kinetic energy of molecules 11. During the electrolysis of aqueous zinc nitrate (A) Zinc plates out at the cathode (B) Zinc plates out at the anode (C) Hydrogen gas, H2 is evolved at the anode (D) Oxygen gas, O2¬ is evolved at the anode 12. If is x2 then will be (A) 3x2 – 2x1 (B) x2 – x1 (C) x2 + x1 (D) 2x1 + 3x2 13. Reaction quotient is Variation of Ecell with log Q is of the type with OA = 1.10 V Ecell will be 1.1591 V when (A) (B) (C) (D) 14. For the half cell At pH = 2, electrode potential is (A) 1.36 V (B) 1.30 V (C) 1.42 V (D) 1.20 V 15. Given Which of the following statements is/are correct? (A) AgNO3 can be stored in copper vessel (B) Cu(NO3)2 can be stored in magnesium vessel (C) CuCl2 can be stored in silver steel (D) HgCl2 can be stored in copper vessel 16. The cell EMF is independent of concentration of the species of the cell in (A) (B) Pt(H2)HClPt(Cl2) (C) ZnZn2+Cu2+Cu (D) Hg, Hg2Cl2KClAgNO3Ag 17. Number of electrons lost during electrolysis of 0.355 g of Cl is (A) 0.01 (B) 0.01No (C) 0.02 No (D) 18. During electrolysis of acidified water, O2 gas is formed at the anode. To produce O2 gas at the anode at the rate of 0.224 c.c. per second at STP, current passed is (A) 0.224 A (B) 2.24 A (C) 9.65 A (D) 3.86 A 19. 0.275 g of metal M is deposited at the cathode due to passage of 1 A of current for 965 s. Hence atomic weight of the metal M is (A) 27.5 (B) 55.0 (C) 110.0 (D) 13.75 20. Same quantity of current is passed through molten NaCl and molten cryolite containing Al2O3. If 4.6 g of sodium were liberated in one cell, the mass of aluminium liberated in other cell was (A) 0.9 g (B) 2.7 g (C) 1.8 g (D) 3.6 g 21. 100 mL of a buffer of 1 M NH3(aq) and 1 M (aq) are placed in two voltaic cells separately. A current of 1.5 A is passed through both cells for 20 minutes. If electrolysis of water only takes place then pH of the (A) LHS half-cell will increase (B) RHS half-cell will increase (C) both half-cells will increase (D) both half-cells will decrease 22. If a steady current of 15.0 is passed through an aqueous solution of CuSO4, how many minutes will it take to deposit 0.250 mol of Cu at the cathode, assuming 100% efficiency? (A) 3.217  103 (B) 1.613  103 (C) 53.62 (D) 0.893 23. Cost of electricity for the production of x LH2 at NTP at cathode is Rs. x, then cost of electricity for the production of x LO2 gas at NTP at anode will be (assume 1 mol of electrons as one unit of electricity) (A) 2x (B) 4x (C) 16x (D) 32x 24. Which has maximum conductivity? (A) [Cr(NH3)3Cl3] (B) [Cr(NH3)4Cl2]Cl (C) [Cr(NH3)5Cl]Cl2 (D) [Cr(NH3)6]Cl3 25. One litre of 1 M CuSO4 solution is electrolysed. After passing 2F of electricity, molarity of CuSO4 will be (A) (B) (C) M (D) 0 26. Borax crystal contains (A) Two triangular units (B) Two tetrahedral units (C) (A) and (B) both (D) None of these 27. Borax is converted into B by steps Borax H3BO3 B2O3 B I and II reagents are (A) acid, Al (B) acid, C (C) acid, Fe (D) acid, Mg 28. On strong heating lead nitrate gives (A) PbO, NO, (B) PbO, NO, (C) PbO, (D) 29. The element with the highest first ionisation potential is (A) Boron (B) Carbon (C) Nitrogen (D) Oxygen 30. Among LiCl, BeCl2, MgCl2 and RbCl, the compound with greatest and least ionic character, respectively are (A) LiCl and RbCl (B) RbCl and BeCl2 (C) RbCl and MgCl2 (D) MgCl2 and BeCl2 31. Which of the following statements is wrong? (A) Anhydrous AlCl3 exists as Al2Cl6 (B) Anhydrous AlCl3 is a trigonal planar molecule (C) Anhydrous AlCl3 fumes in air (D) Anhydrous AlCl3 is ionic 32. The basis for Al as a reducing agent in thermite process is (A) High exothermic hydration of Al3+ (B) High Eox. Pot. of Al (C) High exothermic enthalpy of formation of Al2O3 (D) High I.E. of Al 33. The structures of quartz, mica and asbestos have the same common units of (A) (SiO4)-4 (B) (SiO3)-2 (C) (D) 34. Choose the wrong statement: (A) Ge, Sn and Pb form +2 as well as +4 O.S. (B) Ge2+ and Sn2+ compounds act as reducing agents (C) Pb2+ compounds act as oxidizing agents (D) Stability decreases from Ge2+ to Pb2+ 35. Identify the correct statement wiht respect to carbon monoxide. (A) It combines with water to form carbonic acid (B) It reacts with haemoglobin in red blood cells (C) It is a powerful oxidising agent (D) It is used to prepare aerated drinks 36. The ratio of the rate constant of a reaction at any temperature T to the rate constant T ® ¥ is equal to (A) Energy of activation of the reaction (B) Fraction of molecules in the activated state (C) Average life of the reaction (D) Pre-exponential factor in the Arrhenius equation 37. The rate constant of a reaction: A ¾® B + C at 27°C is 3.0 ´ 10–5 s–1 at 27°C and at this temperature 1.5 ´ 10–4 percent of the reactant molecules are able to cross-over the P.E. barrier. The maximum rate constant of the reaction is (A) 4.5 ´ 10–9s–1 (B) 4.5 ´ 10–11 s–1 (C) 0.2 s–1 (D) 20 s–1 38. For a first order reaction: A B, whose concentration vs. time curve is as shown in the figure. The rate constant is equal to (A) 41.58 h–1 (B) 4.158 s–1 (C) 1.155 ´ 10–3 s–1 (D) 6.93 min–1 39. If DH of a reaction be positive and k1 andk2 be the rate constants of forward reaction and backward reaction, respectively, at temperature t°C k¢1 and k¢2 be the respective rate constants at (t + 10)°C then (A) (B0 (C) (D) None of these 40. Among DH, equilibrium constant (K), rate constant and Ea the one or more than one that is (are) not affected by catalyst is (one) (A) Rate constant and DH (B) K and Ea (C) DH and K (D) Only K 41. For the gaseous reaction is found to be first order with respect to A. If at the starting the total pressure was 100 mm Hg and after 20 minutes it is found to be 400 mm Hg. The rate constant of the reaction is: (A) (B) (C) (D) 42. The decomposition of ozone is believed to occur by the mechanism: , When the concentration of is increased, then the rate (A) increases (B) decreases (C) remains same (D) cannot be predicted 43. In the sequence of the reaction, given that then the rate determining step of the reaction is: (A) (B) (C) (D) 44. What will be the fraction of molecule having energy equal to or greater than activation energy Ea? (A) K (B) A (C) (D) 45. The ratio of the atoms of and in a sample of rock is found to be 4:1. The of is years. How long ago the solidification of the rock could have occurred? (log 2 = 0.30) (A) (B) (C) (D) 46. For the reaction, The kinetic data are as given below: 0.2 0.1 0.4 0.1 0.4 0.2 If for the above reaction is , then the specific reaction rate for the replacement of -OH group of methanol by Cl atom is: (A) (B) (C) (D) 10 47. and DH values of reactions carried out at the same temperature are as given below: At a given temperature and assuming that the backward reactions of all these reactions have the same frequency factor, the rates of in their respective backward reactions are in the increasing order of (A) (B) (C) (D) 48. For the radioactive sequential chain reaction, for the steady state of B, assuming that the no. of atoms of A is half of the no. of atoms of B then if the half life of B is 2 hours then the half of life of A (in hours) will be (A) 4 (B) 2 (C) 1 (D) 3 49. For the given reaction where K is zero order rate constant and b is a first order rate constant concentration of B at any time can be given by the expression. (A) (B) (C) (D) can’t be expressed 50. If 10–5% reactant molecule is crossing over the barrier in transition state at 298K, then find out the activation barrier needed to cross the transition state. (A) 39.94 kJ (B) 49.94kJ (C) 79.94kJ (D) 97.97 kJ Multiple choice questions with more than one option correct 51. Which of the following statements are correct about half-life period? (A) it is proportional to initial concentration for zeroth order (B) average life = 144 half-life for first order reaction (C) time of 75% reaction is thrice of half-life period in second order reaction (D) 99.9% reaction takes place in 100 minutes for the case when rate constant is 0.0693 min1 52. Half-life period is independent of concentration of zinc at constant pH. For the constant concentration of Zn, rate becomes 100 times when pH is decreased from 3 to 2. Hence (A) (B) (C) rate is not affected if concentration of zinc is made four times and that of H+ ion is halved (D) rate becomes four times if concentration of H+ ion is doubled at constant Zn concentration 53. Which of the following statements are correct? (A) it is unimolecular nucleophilic substitution reaction if I or II is formed. (B) it is bimolecular nucleophilic substitution reaction if I or II is formed. (C) it is if I and its enantiomer are formed so that mixture is racemic. (D) it is if II is formed. 54. Rate constant k varies with temperature by equation . We can conclude (A) pre-exponential factor A is 5 (B) E is 2000 kcal (C) pre-exponential factor A is 105 (D) E is 9.212 kcal 55. A reaction is catalysed by H+ ion. In presence of HA, rate constant is 2  103 min1 and in presence of HB rate constant is 1  103 min1, HA and HB both being strong acids, we may conclude (A) equilibrium constant is 2 (B) HA is stronger than HB (C) relative strength of HA and HB is 2 (D) HA is weaker than HB and relative strength is 0.5 56. Electrode potentials of the given half cells Pt(H2)H+(C1); Pt(Cl2)Cl(C2); AgAg+(C3) p1 (I) p2 (II) (III) (A) will increase on increasing C1, C2 and C3 (B) will decrease on increasing C1, C2 and C3 (C) will decrease on increasing C1 and C3 and increase on increasing C2 (D) will remain constant if C1 or C2 is doubled and p1 or p2 is made four times 57. There is blue colour formation if (A) Cu electrode is placed inside AgNO3 solution (B) Cu electrode is placed inside ZnSO4 solution (C) Cu electrode is placed inside dil HNO3 (D) Cu electrode is placed inside dil H2SO4 58. The formation of rust on the surface of iron occurs through the reactions (A) at anode (B) at cathode (C) (D) 59. In which case is zero (A) CuCu2+(0.001 M)Ag+(0.1 M)Ag (B) Pt(H2)pH = 1Zn2+(0.01 M)Zn (C) Pt(H2)pH = 1Zn2+(1 M)Zn (D) Pt(H2)H+(0.01 M)Zn2+(0.01 M)Zn 60. Reactions taking place in a fuel cell are (A) at the cathode (B) reaction in (a) at the anode (C) at the anode (D) reaction in (c) at the cathode 61. It is not advisable to (A) stir sugar solution with a steel spoon (B) stir copper sulphate solution with a silver spoon (C) stir copper sulphate solution with zinc spoon (D) stir silver nitrate solution with a copper spoon 62. By passage of 1 F of electricity (A) 1 mol of Cu is deposited (B) 0.5 mol of Mg is deposited (C) 9 g of Al is deposited (D) 5.6 L of O2 gas evolved at anode 63. In the following electrochemical cell . This will be when (A) [Zn2+] = [H+] = 1 M and pH2 = 1 atm (B) [Zn2+] = 0.01 M, [H+] = 0.1 M and pH2 = 0.01 atm (C) [Zn2+] = 1 M, [H+] = 0.1 M and pH2 = 0.01 atm (D) [Zn2+] = [H+] = 0.1 M and pH2 = 0.1 atm 64. Boron readily dissolves in (A) conc. HCl (B) fused NaOH at 673 K (C) fused Na2CO3 + NaNO3 at 1173 K (D) a mixture of conc. HNO3 and conc. H2SO4 (1 : 2) 65. The allotropic forms of carbon, good conductor of electricity are (A) diamond (B) graphite (C) fullerenes (D) gas carbon Comprehension-I Three students performed three different experiments on electrolysis. Student ‘A’ electrolysied one litre of 1M aqueous solution of KMnO4 till after reduction. The final solution is 0.1 M K2MnO4, student ‘B’ electrolyzed 0.5 L of 2M Ni(NO3)2 solution by passing a current of 9.65 A for 3 hours between nickel electrodes. Student ‘C’ electrolysed NiSO4 solution by passing 12 ampere current but the current efficiency was only 60%. Read the above paragraph carefully and answer the questions given below it: 66. The quantity of electricity used by student A is (A) 0.1 F (B) 1F (C) 10F (D) 100F 67. The molality of the solution left after electrolysis used by student ‘B’ is (A) 0.46 M (B) 0.625 M (C) 0.92M (D) 1.25M 68. The nickel deposited on the cathode per hour in the solution used by student ‘C’ will be (A) 7.883 g (B) 3.941g (C) 5.91 g (D) 2.645 g Comprehension-II Order is an experimental fact for a reaction and molecularity is defined for elementary reactions and depends upon stoichiometric coefficient of a balanced reaction. Order can be fractional but molecularity is always a whole number. For elementary reaction order and molecularity can’t be differentiated. Read the above paragraph carefully and answer the questions given below it: 69. For the multistep reaction and Molecularity of reaction (A) Is n1 + n2 (B) Is (C) Is n1 + 2n2 (D) Can’t be defined 70. Order of reaction in question number 1 (A) Is n1 + n2 (B) Is (C) Is n1 + 2n2 (D) Can’t be predicted 71. For the elementary reaction, Molecularity is (A) 1.5 (B) 3 (C) 0.5 (D) 1 72. For the reaction is question number 3, order of reaction is (A) 3 (B) 1.5 (C) 0.5 (D) 1 73. For chlorination of CH4 in which rate depends upon light only, order and molecularity are …………….. respectively. (A) Two and zero (B) Zero and two (C) Zero and one (D) One and zero Comprehension-III An organic Lewis acid (A) which gives fumes in moist air and intensity of fumes is increased when a rod dipped in NH4OH is brought near to it. An acidic solution of (A) on addition of NH4Cl and NH4OH gives a precipitate (B) which dissolves in NaOH solution. An acidic solution of A does not gives precipitate with H2S. Read the above paragraph carefully and give the answer of following questions: 74. What will be structure of (A)? (A) Planar (B) Trigonal planar (C) Pyramidal (D) Octahedral 75. What will be (A) in above sequence? (A) BF3 (B) AlCl3 (C) GaCl2 (D) ZnCl2 76. The intensity of fumes increase due to the formation of– (A) NH4OH (B) HCl (C) NH4Cl (D) NaAlO2 77. The soluble product obtained when the precipitate (B) dissolves in NaOH, is: (A) Al2O3 (B) NaAlO2 (C) Na2AlO2 (D) None 78. Chloride of compound (A) does not show bonding because: (A) Absence of vacant orbital (B) Larger size of compound (A) (C) Smaller size of compound (A) (D) None Comprehension-IV A metal is regarded as an assembly of metal ions and free electrons. When the metal is in contact with water, some metal ions enter into the liquid due to a tendency in the metal, called by Nernst as “Electrolytic solution tension”. An alloy of 1.45 gm Ag and Si was dissolved in desired amount of HNO3 and volume made upto 500 ml. An Ag electrode was dipped in solution and Ecell of the cell is Read the above paragraph carefully and answer the questions given below: 79. Observed concentration of Ag+ in the cell (A) 2.25 × 10–9 M (B) 9.25 × 10–6 M (C) 9.25 × 10–7 M (D) 9.25 × 10–5 M 80. % weight of Pb metal in above alloy sample is (A) 99.25% (B) 89.95% (C) 99.96% (D) 82.35% 81. The emf of the cell involving the reaction, is 0.80 V. The standard oxidation potential of Ag electrode is (A) 0.80 V (B) –0.80 V (C) 0.40 V (D) 0.20 V 82. In the above cell, reaction cathodic cell reaction is (A) (B) (C) Both (A) and (B) (D) None of the above 83. Which of the following statement is correct? (A) Oxidation number of oxygen in KO2 is +1. (B) The specific conductance of an electrolytic solution decreases with increase in dilution. (C) Sn2+ oxidizes Fe3+. (D) Zn/ZnSO4 is a reference electrode. Match The Following 84. Match List-I with List-II List-I List-II (A) XeF2 (P) Square pyramidal (B) PCl5 (Q) Linear shape (C) XeOF4 (R) sp3d hybridization (D) XeF4 (S) sp3d2 85. Match List-I with List-II: List-I List-II (A) He (P) London dispersion force (B) Xe (Q) Lowest boiling noble gas (C) XeF6 (R) sp3d3 (D) IF7 (S) Distorted octahedral 86. Match List–I and List–II. LIST-I LIST-II (a) Rate constant has the same unit as the rate of reaction. (i) One (b) Reactions having apparent molecularity more than three. (ii) Zero order reaction (c) Reactions having molecularity two but order of reaction is one. (iii) Complex reaction (d) The syum For a reaction, A ® B, the rate of reaction doubles as the concentration of A is doubled. (iv) Pseudo unimolecular reaction a b c d (A) ii iv iii i (B) ii iii iv i (C) iii ii iv i (D) ii iv i iii 87. Match list – I with list – II and choose the correct answer from the code given below List – I List – II (a) Half life period of first order reaction (i) (b) Molecular concentration (ii) (c) Temperature coefficient (iii) active mass (d) Half life period of zero order reaction (iv) Code is a b c d (A) (ii) (iii) (i) (iv) (B) (i) (ii) (iii) (iv) (C) (ii) (iii) (iv) (i) (D) (iii) (iv) (i) (ii) 88. Match List-I with List-II and List-III: List-I List-II List-III (Quantity) (Symbol) (Unit) (a) Conductivity (p) (u) mho cm-1 (b) Cell constant (q) (v) cm-1 (c) Molar conductance (r) (w) ohm-1 cm2 mol-1 (d) Equivalent conductance (s) l/A (x) ohm-1 cm2 eq-1 89. Match the salts in Column-I with their use in Column-II: Column-I Column-II (a) Hg2Cl2 (p) Salt bridge (b) Agar-agar (q) Calomel electrode (c) 0.1 N KCl (r) Used in ice cream (d) Quinhydron (s) Redox electrode ANSWERS TO WORK BOOK Subjective: Board Type Questions 1. Percentage of Ag = 0.0296% 2. 1.4336 cm-1 3. 0.31045 volt 4. 1.70 V 5. 41239.4 C 6. The reactions are (i) Fe (s) ¾® Fe+2 (aq) + 2e–, (ii) 2H+ + (g) + 2e- ¾® H2O (l), E0 = +1.23V Adding equation (i) and (ii), we get Fe (s) + 2H+ + (g) ¾® Fe+ (aq) + H2O (l), = 1.67V \ = positive = 1.67V \ DG0 is negative. So, the reaction is thermodynamically favourable or spontaneous. 7. - 14.76 J K-1 mol-1. 8. 12. 25 mL of a solution of HCl (0.1M) is being titrated potentiometrically against 0.1 M NaOH solution using a hydrogen electrode as the indicator electrode and saturated calomel electrode (SCE) as the reference electrode. What would be the EMF of the cell initially and after the addition of 20 mL of alkali at 25°C? Given Reduction potential of SCE = 0.2422V. [log 9 = 0.95]. 9. (b) It is because of the presence of polar water molecules which stabilizes Al3+ ion and increases the ionic character of Al–Cl bonds. (c) As the hydration energy of BaSO4 is less than its lattice energy, it is insoluble in water. 10. Maximum coordination of boron is four as it does not have d-orbitals while the maximum coordination numbers of aluminium is 6. Thus, Al forms [AlF6]3– ion while boron does not form [BrF6]3– ion. 11. 2CH3Cl + Si (CH3)2SiCl2 12. Because Al is highly active metal and its affinity towards oxygen is very high. At high temperature, reacting with carbon it converts into Al4C3 instead of free metal. 13. A gives dirty yellow ppt. soluble in yellow ammonium sulphide \ (A) has Sn2+ A gives chromyl chloride test of Cl– \ (A) is SnCl2 Reaction 14. Al(OH)3 is soluble in NaOH forming NaAlO2, Fe(OH)3 is insoluble. 15. 16.¬¬¬¬ K = 17. Multiplying equation (ii) by 2 and adding (i) we get Cl2 + 2CO 2COCl \K1 = [COCl] = …(1) \ Slowest step is rate determining step hence Rate = K1(COCl] [Cl2] …(2) From equation (1) & (2) we get : Rate = K1 \Rate = K¢[CO] [Cl2]3/2 18. 19. T = 311.2 K 20. 21. No of a-particles = 8 No of b particles =6 22. t1/2 = 5 year t = 15 year \ n = Let original amount be No and amount after time t be N \ N = Hence (⅛)th of the original amount left. 23. 280 days. 24. K = 2.66´108 lit mol-2 sec-1 at 300 K 25. (a) Initial rate (R1) = K [ ]1=1´10-2´(1) = 1´10-2 \ Initial rate = 1´10-2 ml Lt -1 sec-1 (b) K = Þ 1´10-2 = (t = 1 minute= 60 sec) \ (1-x) = 0.549 Rate after 1 minute (R2) = K´ [ ]1 =10-2´0.549 = 5.49´10-3 mol Lt -1 Sec-1 26. t = 3920 years. 28. Rate of a reaction may be defined as the change in any one of the reactants or products per unit time. 29. 30. Rate of disappearance of Br- = = 31. It is defined as the rate of a chemical reaction when the concentration of each reactant appearing in the rate equation is taken as unity. 32. The units of rate constant is L mol-1s-1 or (mol L-1)-1s-1+. Equate this with general expression of (mol L-1)1-ns-1. \ -1 = 1 - n or n = 2 The order of reaction = 2 33. (i) Rate of a reaction = atm (min)-1 (ii) Rate constant = atm-1/2 min-1 34. In the absence of Hbr, the rate equation is reduced to and the overall order is 35. (i) r = k[NH3]° (ii) r = k[NH4NO2] 36. where k = rate constant [R]0 = initial concentration of the reactant [R] = concentration of the reactant at time, t. 37. (i) At very low concentration of NH3, 1 + k2[NH3] » 1. \ Rate = k1 [NH3] and order of reaction = 1 (ii) At very high concentration of NH3, 1 + k2[NH3] » k¬2[NH3] \ order of reaction = 0 38. As rate is independent of the concentration the order of the reaction is zero. 39. The half-life of a reaction is defined as the time required for the reaction to be 50% complete. It is also defined as the time during which the concentration of reactant is reduced to one half of its initial concentration. 40. The order of the reaction is one, as t1/2 is independent of the concentration of the reactant. IIT Level Questions 41. Ea = 100 KJ 42. Moles of He formed at STP= 3´3 = 9/4 Volume of He at STP = 9/4´22.4 =50.4 lt 43. V = 5.95´103 ml = 5.95 L 44. 0.99 V 45. Ksp = 2.287 ´ 10–12 mol3 liltre–3 46. (i) (A) is characteristic dimerised compound which sublimes in 180°C and forms monomer if heated to 400°C and thus (A) is (AlCl3)2 or Al2Cl¬6. Al2Cl6(s) Al2Cl4(s) 2AlCl3 (ii) It fumes with wet air Al2Cl4 + 6H2O 2Al(OH)3¯ + 6HCl­ (iii) 2AlCl3 + 6H2O 2Al(OH)3¯ + 6HCl(s) (iv) (A) gives white ppt. with NH4OH and NaOH, soluble in excess of NaOH Al2Cl6 + 6NH4OH ¾® 2Al(OH)3 + 6NH4Cl Al2Cl6 + 6NaOH ¾® 2Al(OH)3 + 6NaCl 2NaAlO2 + 2H2O 47. The rate of reaction decreases continuously with time except for a zero order reaction. Therefore, average rate of reaction has no significance for the reaction. But instantaneous rate of reaction for a given instant of time does not change with time. 48. Rate of reaction Rate constant (i) It is defined as the change in concentration of the reactant or product with time, each divided by its stoichimetric coefficient. (i) It is defined as the rate of chemical reaction when the concentration of each reactant appearing in the rate equation is taken as unity. (ii) It always has a unit of (conc)/time. (ii) Its units depends on the order of a reaction. For nth order reaction the units of rate constant = (conc)1-n time-1 (iii) It depends on the initial concentration of the reactants. (iii) It is independent of the initial concentration of the reactants. 49. The order of a reaction is defined as the sum of the exponents to which each concentration terms is raised in the experimently derived rate equation. For example in the reaction A + B + C ¾® Products and the rate law expression is Then, overall order of reaction = x + y + z. Order of a reaction can be fractional value. An example of a fractional reaction is gas-phase decomposition of CH3CHO. and 50. Objective: Single Correct Questions 1. A 2. A 3. A 4. A 5. A 6. B 7. C 8. D 9. B 10. B 11. D 12. A 13. B 14. C 15. C 16. A 17. B 18. D 19. B 20. C 21. B 22. C 23. A 24. D 25. D 26. C 27. D 28. D 29. C 30. B 31. D 32. C 33. A 34. D 35. B 36. B 37. D 38. C 39. C 40. C 41. C 42. B 43. A 44. D 45. B 46. B 47. D 48. C 49. C 50. A Multiple Correct Questions 51. A,B,C,D 52. B,C,D 53. C,D 54. C,D 55. B,C 56. C,D 57. A,C 58. A,B,C,D 59. A,B 60. A,C 61. C,D 62. B,C,D 63. A,B,C 64. C,D 65. B,D Comprehension 66. A 67. C 68. A 69. D 70. C 71. B 72. A 73. B 74. B 75. B 76. C 77. B 78. B 79. B 80. C 81. A 82. C 83. B Match The Following 84. (A-Q,R) (B-R) (C-P,S) (D-S) 85. (A-P,Q) (B-P) (C-R,S) (D-R) 86. B 87. A 88. (a-q-u), (b-s-v), (c-p-w ), (d-r-x) 89. (a - q), (b - p, r), (c - p), (d - s)