Physical Chemistry Past Paper PDF

PHYSICAL CHEMISTRY S.No. CONTENTS Page 1. Surface Chemistry 01 2. Chemical kinetics 05 3. Solution & Colligative properties 11...

PHYSICAL CHEMISTRY S.No. CONTENTS Page 1. Surface Chemistry 01 2. Chemical kinetics 05 3. Solution & Colligative properties 11 4. Electrochemistry 15 5. Solid State 20 6. Chemical Equilibrium 25 7. Thermodynamics & Thermochemistry 31 8. Redox Reaction 38 9. Ionic Equilibrium & Acid Base 42 10. Mole Concept & Gaseous state 47 E  Surface Chemistry ALLEN SURFACE CHEMISTRY EXERCISE-I 1. The size of the colloidal particles is in between: 10. When freshly precipitated Fe(OH)3 is boiled with (1) 10–7 – 10–9 cm. (2) 10–9 – 10–11 cm. water in the presence of few drops of dil HCl, a (3) 10–5 – 10–7 cm. (4) 10–2 – 10–3 cm. hydrated ferric hydroxide sol is obtained. This 2. Peptization is a process of : method is termed as :– (1) Dialysis (2) Peptization (1) Precipitating the colloidal particles (3) Ultrafiltration (4) Electrodispersion (2) Purifying the colloidal sol 11. To coagulate Pt sol, which of the following is most (3) Dispersing the precipitate into colloidal sol effective :– (4) Movement of colloidal particles towards the (1) NaCl (2) Na3PO4 oppositely charged electrodes (3) AlCl3 (4) Alcohol 3. Colloids are purified by : 12. A colloidal mixture of Fe(OH)3 in water is :– (1) Brownian motion (2) Precipitation (1) A hydrophilic colloid (3) Dialysis (4) Filtration (2) A hydrophobic colloid 4. Flocculation value is expressed in terms of: (3) An emulsion (4) None (1) Millimole per litre (2) Mol per litre 13. A catalyst is a substance which : (1) Increases the equilibrium concentration of the (3) Gram per litre product (4) Mol per millilitre (2) Change the equilibrium constant of the reaction 5. Which is kinetic phenomenon? (3) Shortens the time to reach equilibrium (1) Brownian motion (4) Supplies energy to the reaction 14. Which of the following statement is more correct: (2) Tyndall effect (1) Catalyst only accelerates the rate of a chemical (3) Both (1) and (2) reaction (4) None of these (2) A catalyst can retard the rate of a chemical 6. The heats of adsorption in physisorption lie in the reaction range (in KJ mol–1) : (3) A catalyst does not affect the speed of a reaction (1) 40-400 (2) 40-100 (4) A catalyst alters the speed of a reaction (3) 20-40 (4) 1-10 15. Efficiency of the catalyst depends on its :– 7. According to Langmuir adsorption isotherm, the (1) Molecular weight amount of gas adsorbed at very high pressure : (2) Number of free valencies (1) Reaches a constant limiting value (3) Physical state (4) Amount used (2) Goes on increasing with pressure 16. In a reversible reaction, a catalyst :– (3) Goes on decreasing with pressure (1) Increases the rate of forward reaction only (4) Increases first and decreases later with pressure (2) Increases the rate of forward reaction to a node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\01-Surface Chemistry.p65 8. Which one of the following is an incorrect statement greater extent that of the backward reaction for physisorption : (3) Increases the rate of forward reaction and (1) It is a reversible process decreases that of the backward reaction (2) It requires less heat of adsorption (4) alters the rate of forward and backward reaction equally (3) It requires activation energy 17. Which is false for catalyst :– (4) It takes place at low temparature (1) A catalyst can initiate a reaction 9. Lyophobic colloids are :– (2) It does not alter the position of equilibrium in (1) Reversible a reversible reaction (2) Irreversible (3) A catalyst remains unchanged in quality and composition at the end of reaction (3) Water loving (4) Catalysts are sometimes very specific in respect (4) Solvent loving of a reaction E 1 JEE ( Main) - Chemistry ALLEN 18. Shape selective catalysts are so called because 25. Given below are a few electrolytes, indicate which of : one among them will bring about the coagulation (1) The shape of the catalysts of a gold sol. quickest and in the least of molar (2) The specificity of the catalysts concentration? (3) The size of the pores of the catalysts which can (1) NaCl (2) MgSO4 trap only selective molecules (3) Al2(SO4)3 (4) K4[Fe(CN)6] (4) Their use for only some selected reactions 26. The minimum concentration of an electrolyte 19. Which gas will be adsorbed on a solid to greater required to cause coagulation of a sol is called extent. (1) flocculation value (2) gold number (1) A gas having non polar molecule (3) protective value (4) none of these (2) A gas having highest critical temperature (Tc) 27. Which one of following statements is not correct in (3) A gas having lowest critical temperature. respect of lyophilic sols? (4) A gas having highest critical pressure. (1) There is a considerable interaction between the dispersed phase and dispersion medium 20. The nature of bonding forces in chemisorption (2) These are quite stable and are not easily (1) purely physical such as Van Der Waal's forces coagulated (2) purely chemical (3) They need stabilizing agent (3) both chemical and physical simultaneously. (4) The particle are hydrated (4) none of these 28. At the critical micelle concentration (CMC) the 21. The Tyndall effect associated with colloidal particles surfactant molecules is due to (1) decompose (1) presence of electrical charges (2) dissociate (2) scattering of light (3) associate (3) absorption of light (4) become completely soluble (4) reflection of light 29. Although nitrogen does not adsorb on surface at 22. Which one of the following is not applicable to room temperature, it adsorbs on surface at 83K. chemisorption? Which one of the following statements is correct - (1) Its heat of adsorption is high (1) At 83K, there is formation of monomolecular (2) It takes place at high temperature layer (3) It is reversible (2) At 83K, there is formation of multimolecular (4) It forms mono-molecular layers layer 23. Milk is an example of (3) At 83K, nitrogen molecules are held by chemical (1) emulsion (2) suspension bonds (3) foam (4) sol. (4) At 83K, nitrogen is adsobed as atoms. 24. Colloidal particles in a sol. can be coagulated by 30. The volume of a colloidal particle VC , volume of (1) heating a solute particle in a true solution Vt , the volume (2) adding an electrolyte of suspension particle is VS can be arranged (3) adding oppositely charged sol (1) VC = Vt = VS (2) VS < VC < Vt (4) any of the above methods (3) VS > VC > Vt (4) VC > VS > Vt node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\01-Surface Chemistry.p65 ANSWER KEY Exercise-I Que. 1 2 3 4 5 6 7 8 9 10 Ans. 3 3 3 1 1 3 1 3 2 2 Que. 11 12 13 14 15 16 17 18 19 20 Ans. 3 2 3 4 2 4 1 1 2 2 Que. 21 22 23 24 25 26 27 28 29 30 Ans. 2 3 1 4 3 1 3 3 2 3 2 E  Surface Chemistry ALLEN PREVIOUS YEARS' QUESTIONS EXERCISE-II 1. Gold numbers of protective colloids A, B, C and 6. If x is the mass of the gas adsorbed on mass m of the D are 0.50, 0.01, 0.10 and 0.005 respectively. absorbent at pressure p, Freundlich adsorpton The correct order of their protective power is :- isotherm gives a straight line on plotting :- [AIEEE-2008] [AIEEE-2012 (Online)] (1) D < A < C < B (2) C < B < D < A x x (3) A < C < B < D (4) B < D < A < C (1) vs p (2) log vs log p m m 2. Which of the following statements is incorrect regarding physissorptions ? [AIEEE-2009] x 1 x (1) Under high pressure it results into multi (3) log vs p (4) vs p m m molecular layer on adsorbent surface (2) Enthalpy of adsorption (DHadsorption) is low and 7. Fog is a colloidal solution of :- positive [AIEEE-2012 (Online)] (3) It occurs because of Van der Waal's forces (1) Gaseous particles dispersed in a liquid (4) More easily liquefiable gases are adsorbed (2) Solid particles dispersed in a liquid readily (3) Liquid particles dispersed in gas 3. Among the electrolytes Na2SO4, CaCl2, Al(SO4)3 (4) Solid particle dispersed in gas and NH4Cl, the most effective coagulating agent 8. The coagulating power of electrolytes having ions for Sb2S3 sol is : [IIT-2009] Na+, Al3+ and Ba2+ for aresenic sulphide sol (1) Na2SO4 increases in the order :- [JEE (MAIN) 2013] (2) CaCl2 (1) Al3+ < Ba2+ < Na+ (2) Na+ < Ba2+ < Al3+ (3) Al2(SO4)3 (3) Ba2+ < Na+ < Al3+ (4) Al3+ < Na+ < Ba2+ (4) NH4Cl 9. The migration of dispersion medium under the 4. The correct statement(s) pertaining to the influence of an electric potential is called : adsorption of a gas on a solid surface is (are) - [JEE (MAIN) 2013 (Online)] [IIT-2011] (1) Electrophoresis (2) Cataphoresis (1) Adsorption is always exothermic (3) Electroosmosis (4) Sedimentation (2) Physisorption may transform into chemisorption 10. Smoke is an example of :[JEE (MAIN) 2013 (Online)] at high temperature (1) Solid dispersed in solid (3) Physisorption increases with increasing (2) Solid dispersed in gas temperature but chemisorption decreases with (3) Gas dispersed in solid increasing temperature (4) Gas dispersed in liquid (4) Chemisorption is more exothermic than 11. For a linear plot of log(x/m) versus log p in a physisorption, however it is very slow due to Freundlich adsorption isotherm, which of the higher energy of activation following statements is correct ? (k and n are node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\01-Surface Chemistry.p65 5. According to Freundlich adsorption isotherm, which constants) [JEE (MAIN) 2016] of the following is correct ? [AIEEE-2012] (1) log (1/n) appears as the intercept (2) Both k and 1/n appear in the slope term x (1) µ p0 (3)1/n appears as the intercept m (4) Only 1/n appears as the slope x 12. Gold numbers of some colloids are : (2) µ p1 Gelatin : 0.005 – 0.01, Gum Arabic : m 0.15 – 0.25 ; Oleate : 0.04 – 1.0, x Starch : 15 – 25. Which among these is a better (3) µ p1/ n m protective colloid ? (4) All the above are correct for different ranges of [JEE (MAIN) 2016 (Online)] pressure (1) Oleate (2) Gelatin (3) Gum-Arabic (4) Starch E 3 JEE ( Main) - Chemistry ALLEN 13. A particular adsorption process has the following 16. Among the following, correct statement is : characteristics: (i) It arises due to van der Waals [JEE-Main (online)2017] forces and (ii) it is reversible. Identify the correct (1) One would expect charcoal to adsorb chlorine statement that describes the above adsorption more than hydrogen sulphide. process : [JEE (MAIN) 2016 (Online)] (2) Brownian movement is more pronounced for (1) Enthalpy of adsorption is greater than 100 kJ mol–1 smaller particles than for bigger-particles. (2) Energy of activation is low. (3) Hardy Schulze law states that bigger the size of (3) Adsorption is monolayer the ions, the greater is its coagulating power (4) Adso rptio n increase s with increase in (4) Sols of metal sulphides are lyophilic temperature. 17. Adsorption of a gas on a surface follows Freundlich 14. For a linear plot of log(x/m) versus log p in a x Freundlich adsorption isotherm, which of the adsorption isotherm. Plot of log versus log p gives following statements is correct ? (k and n are m constants) [JEE (MAIN) 2016 (Offline)] a straight line with slope equal to 0.5, then : (1) log (1/n) appears as the intercept [JEE-Main (online)2017] (2) Both k and 1/n appear in the slope term x (3) 1/n appears as the intercept ( is the mass of the gas adsorbed per gram of m (4) Only 1/n appears as the slope adsorbent) 15. The Tyndall effect is observed only when following (1) Adsorption is proportional to the square of conditions are satisfied :- [JEE (MAIN) 2017] pressure. (a) The diameter of the dispersed particles is much (2) Adsorption is independent of pressure. smaller than the wavelength of the ligh used. (3) Adsorption is proportional to the pressure. (b) The diameter of the dispersed particle is not (4) Adsorption is proportional to the square root of much smaller than the wavelength of the light pressure. used. 18. Which one of the following is not a property of (c) The refractive indices of the dispersed phase and physical adsorption [JEE-Main (online)2018] dispersion medium are almost similar in (1) Unilayer adsorption occurs magnitude. (2) Greater the surface area, more the adsorption (d) The refractive indices of the dispersed phase and (3) Lower the temperature, more the adsorption dispersion medium differ greatly in magnitude. (4) Higher the pressure, more the adsorption (1) (a) and (d) (2) (b) and (d) (3) (a) and (c) (4) (b) and (c) node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\01-Surface Chemistry.p65 PREVIOUS YEARS QUESTIONS ANSWER KEY Exercise-II Que. 1 2 3 4 5 6 7 8 9 10 Ans. 3 2 3 1,2,4 4 2 3 2 3 2 Que. 11 12 13 14 15 16 17 18 Ans. 4 2 2 4 2 2 4 1 4 E  Chemical kinetics ALLEN CHEMICAL KINETICS EXERCISE-I 1. In a reaction N2(g) + 3H2(g)¾®2NH3(g), the rate 6. For the first order decomposition of SO2Cl2(g), of appearance of NH3 is 2.5 × 10–4 mol L–1 sec–1. SO2Cl2(g) ® SO2(g) + Cl2(g) a graph of log (a0 – x) The rate of reaction & rate of disappearance of vs t is shown in figure. What is the rate constant (sec–1)? H2 will be (In molL–1sec–1) Time (min) ® (1) 3.75 × 10–4, 1.25 × 10–4 2 4 6 8 10 (0,0) (2) 1.25 × 10–4, 2.5 × 10–4 | | | | | log (a0 – x) (3) 1.25 × 10–4, 3.75 × 10–4 -1– (4) 5.0 × 10–4, 3.75 × 10–4 -2– 2. The rate constant of a zero order reaction is 0.2 mol dm-3h-1. If the concentration of the reactant -3– after 30 minutes is 0.05 mol dm-3. Then its initial (1) 0.2 (2) 4.6 × 10–1 concentration would be : (3) 7.7 × 10 –3 (4) 1.15 × 10–2 (1) 0.15 mol dm-3 7. At certain temperature, the half life period for the (2) 1.05 mol dm-3 thermal decomposition of a gaseous substance (3) 0.25 mol dm-3 depends on the initial partial pressure of the substance as follows (4) 4.00 mol dm-3 P(mmHg) 500 250 3. Which graph represents zero order reaction [A(g) ® B(g)] : t1 2 (in min.) 235 950 Find the order of reaction [Given log (23.5) = 1.37 ; log (95) = 1.97; d[B] log 2 = 0.30] (1) [B] (2) dt (1) 1 (2) 2 (3) 2.5 (4) 3 8. For a reaction A ¾¾ ® Product t t t1/2 1 tan – 1 (4 × 1 0 – 5 ) (3) (4) t3/4 [A ] 2 [A]0 [A]0 tim e (se c) 4. A reaction is of first order. After 100 minutes, 75 g of the reactant A are decomposed when 100g What is the value of k for the given reaction- are taken initially. Calculate the time required when 4 150g of the reactant A are decomposed, the initial (1) 4 × 10–5 M–1s–1 (2) × 10–5 M–2s–1 3 weight taken is 200g. 2 (1) 100 minutes (3) 2 × 10–5 M–2s–1 (4) × 10–5 M–2s–1 3 (2) 200 minutes 9. For a 1st order homogeneous gaseous reaction (3) 150 minutes A ® 2B + C, if the pressure after time t was Pt and node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\02-Chemical kinetics.p65 (4) 175 minutes after long time was P¥ , then rate constant (k) in 5. Consider the reaction : terms of Pt & P¥ and t is - A ¾® B + C 2.303 æ P¥ ö Initial concentration of A is 1 M. 20 minutes time is (1) k = log ç ÷ required for completion of 80 % reaction. t è P¥ - Pt ø d[ B] 2.303 æ 2P¥ ö If = k[A], then half life (t1/2 ) is (2) k = log ç ÷ dt t è P¥ - Pt ø (Use : ln 5 = 1.6, ln2 = 0.7) 2.303 æ 2P¥ ö (1) 55.44 min. (2) 50 min (3) k = log ç ÷ t è 3(P¥ - Pt ) ø (3) 8.75 min (4) 12.5 min (4) None of these E 5 JEE ( Main) - Chemistry ALLEN 10. Activation energy of a reaction is – 15. Thermal decomposition of compound X is a first (1) The energy released during the reaction order reaction. If 75% of X is decomposed in (2) The energy evolved when activated complex is 100 min. How long will it take for 90% of the formed compound to decompose?Given : log 2 = 0.30 (3) Minimum amount of energy needed to (1) 190 min (2) 176.66 min overcome the potential barrier of reaction (3) 166.66 min (4) 156.66 min (4) The energy needed to form one mole of the 16. For the reaction A + B ® product, product Given : [A]0 = [B]0 11. For producing the effective collisions, the colliding List-I List-II (Observed Rate Law) is- (Graph) molecules must possess:- Conc. (1) A certain minimum amount of energy (2) Energy equal to or greater than threshold energy (P) r = k[A] (1) (3) Proper orientation [A] (4) Thres h old en ergy as well as proper Time orientation of collision t1/2 12. For the first order reaction A ¾® B + C, carried out at 27 ºC if 3.8 × 10–16 % of the reactant (Q) r = k[A]1/2[B]1/2 (2) molecules can overcome energy barrier, the Ea [A]0 (activation energy) of the reaction is [log 3.8=0.58, 2.303 × 8.314 ×17.42 = 333.33] ln t1/2 (1) 12 kJ/mole (2) 831.4 kJ/mole (3) 100 kJ/mole (4) 111.11 J/mole (R) r = k[A] [B] (3) 135º 13. The following mechanism has been proposed for ln[A]0 the exothermic catalyzed complex reaction. k ln[A]t k A+B I AB ¾¾® 1 AB + I ¾¾® 2 P+A 0 If k1 is much smaller than k2. The most suitable (S) r = k[A] [B] (4) Time qualitative plot of potential energy (P.E.) versus reaction coordinate for the above reaction. Code : P Q R S (1) 4 1 3 2 (2) 2 3 1 4 (3) 1 2 3 4 (1) (2) (4) 4 3 2 1 Match the Columns for Reaction A ® P Column - I Column - II Column - III (I) First (i) Reaction complete (P) Rate depends on Order in finite time concentration (II) Second (ii) Reaction complete (Q) After equal interval Order in infinite time of time concentration of reactant left are in G.P. (III) Third (iii) Half life is independent (R) After equal interval (3) (4) Order of concentration of of time concentration node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\02-Chemical kinetics.p65 reactant of reactant left are in A.P. (IV) Zero (iv) Half life decreases (S) Half life depends on Order when concentration temperature 14. Which of the following is INCORRECT for first of reactant increases order reaction ? 17. For the reaction H2 + I2 2HI, the true (1) On introducing catalyst, both rate constant and relationship is - rate of reaction increases. d [H 2 ] d[I 2 ] d[HI] (2) On increasing temperature both rate constant (1) – = = dt dt dt & rate of reaction increases. d [H 2 ] d[I 2 ] 1 d[HI] (3) On decreasing volume both rate constant & rate (2) = – = dt dt 2 dt of gaseous reaction increases. (4) On increasing concentration of gaseous reactant 2d[H2 ] 2d[I2 ] d[HI ] (3) – = – = at constant volume & constant temperature dt dt dt both total pressure and rate of the reaction 2d[H2 ] 2d[I2 ] 1 d[HI] increases. (4) = – = dt dt 2 dt 6 E  Chemical kinetics ALLEN 18. A chemical reaction [2A] + [2B] + [C] ––® product 25. Consider an endothermic reaction : X ® Y with follows the rate equation : r µ [A] [B]2 then order the activation energies Eb and Ef for the backard of reaction is - and forward reactions, respectively. In general (1) 0 (2) 1 (3) 2 (4) 3 (1) Eb > Ef 19. The unit of rate constant of first & second order (2) Eb < Ef reaction is respectively - (3) there is no definite relation between Eb and Ef (1) time–1, mole–1. litre. time–1 (4) Eb = Ef (2) mole–1 litre–1, time–1 (3) mole–1. litre. time–1, time–1 26. A reaction involving two different reactant can (4) sec–1, litre–1 never be - 20. In the equation kt = ln C0 – ln Ct , the curve (1) first order reaction between t and ln Ct is - (2) unimolecular reaction (1) a straight line (2) a parabola (3) biomolecular reaction (3) a hyperbola (4) none of these (4) second order reaction 21. In respect of the equation k = Ae–Ea/RT in chemical 27. Which of the following statement(s) is (are) correct kinetics, which one of the following statement is (1) A plot of log Kp versus 1/T is linear correct ? (2) A plot of log [X] versus time is linear for a first (1) Ea is energy of activation order reaction, X ¾® P (2) R is Rydberg's constant (3) A plot of log P versus 1/T is linear at constant (3) k is equilibrium constant volume. (4) A is adsorption factor (4) A plot of P versus 1/V is linear at constant 22. For the reaction system : 2NO(g)+O2(g)®2NO2(g) volume is suddenly reduced to half its value by temperature. increasing the pressure on it. If the reaction is of 28. The rate constnat for the reaction first order with respect to O2 and second order 2N2O5 ¾® 4NO2+O2 with respect to NO,the rate of reaction will – is 3.0 × 10–5 sec–1. if the rate is 2.4 × 10–5 mol (1) Increase to eight times of its initial value litre –1 sec–1, then the concentration of N2O 5 (2) Increase to four times of its initial value (in mol litre–1 ) is (3) Diminish to one-fourth of its initial value (1) 1.4 (2) 1.2 (3) 0.004 (4) 0.8 (4) Diminish to one-eight of its initial value 29. In a first order reaction the concentration of reactant 23. The rate law for a reaction between substances A decreases from 800 mol/dm3 to 50 mol/dm3 in and B is given by, Rate = k [A]n [B]m. On doubling 2 × 104 sec. The rate constant of reaction in sec–1 the con centration of A and halving the is concentration of B, the ratio of the new rate to (1) 2 × 104 (2) 3.45 × 10–5 the earlier rate of the reaction will be as : (1) (n – m) (2) 2(n – m) (3) 1.3486 × 10–4 (4) 2 × 10–4 30. The reaction, X ¾® Product follows first order 1 kinetics. In 40 minutes the concentration of X (3) (4) (m + n) 2( m + n ) changes from 0.1 M to 0.025 M. Then the rate of 24. The rate equation for the reaction 2A+B ® C is reaction when concentration of X is 0.01 M found to be : rate= k[A][B]. The correct statement (1) 1.73 × 10 –4 M min –1 in relation to this reaction is that the (2) 3.47 × 10 –5 M min –1 (1) rate of formation of C is twice the rate of node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\02-Chemical kinetics.p65 (3) 3.47 × 10 –4 M min –1 disappearance of A. (4) 1.73 × 10 –5 M min –1 (2) Half life is a constant (3) unit of k must be s–1 (4) value of k is independent of the initial concentrations of A and B ANSWER KEY Exercise-I Que. 1 2 3 4 5 6 7 8 9 10 Ans. 3 1 4 1 3 3 4 3 3 3 Que. 11 12 13 14 15 16 17 18 19 20 Ans. 4 3 1 3 3 1 3 4 1 1 Que. 21 22 23 24 25 26 27 28 29 30 Ans. 1 1 2 4 2 2 1,2,4 4 3 3 E 7 JEE ( Main) - Chemistry ALLEN PREVIOUS YEARS' QUESTIONS EXERCISE-II 1. t 1/4 can be taken as the time taken for the 7. Consider the reaction: concetration of a reactant to drop to 3/4 of its Cl2(aq) + H2S(aq) ® S(s) + 2H+(aq) + 2Cl–(aq) initial vlaue. If the rate constant for a first order The rate equation for this reaction is reaction is k, then t1/4 can be written as - rate = k[Cl2][H2S] [ln2 = 0.7, ln3 = 1.11] [AIEEE-2005] Which of these mechanisms is/are consistent with (1) 0.29/k (2) 0.10/k this rate equation ? [AIEEE-2010] (3) 0.75/k (4) 0.69/k A. Cl2 + H2S ® H+ + Cl– + Cl+ + HS– (slow) 2. A reaction was found to be second order with Cl+ + HS– ® H+ + Cl– + S(fast) respect to the concentration of carbon monoxide. B. H2S Û H+ + HS– (fast equilibrium) If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of Cl2 + HS– ® 2Cl– + H+ + S(slow) reaction will [AIEEE-2005] (1) A only (1) triple (2) B only (2) increase by a factor of 4 (3) Both A and B (3) double (4) Neither A nor B (4) remain unchanged 8. The time for half life period of a certain reaction 3. Rate of reaction can be expressed by Arhenius A ¾® Products is 1 hour, when the initial equation as k = Ae–E/RT. In this equation, E concentration fo the reactant 'A' is 2.0 mol L–1, How represents [AIEEE-2005] much time does it take for its concentration to come (1) the energy below which colliding molecules will from 0.50 to 0.25 mol L–1 if it is a zero order not react reaction ? [AIEEE-2010] (2) the total energy of the reacting molecule at a temperature, T (1) 1 h (2) 4 h (3) The fraction of molecules with energy greater (3) 0.5 h (4) 0.25 h than the activation energy of the reaction 9. The concentration of R in the reaction R ® P was (4) None of these measured as a function of time and the following 4. The following mechanism has been proposed for the data is obtained : reaction of NO with Br2 to form NOBr NO(g) + Br2(g) NOBr2(g) [R] (molar) 1.0 0.75 0.40 0.10 NOBr2(g) + NO(g) ® 2NOBr(g) t(min.) 0.0 0.05 0.12 0.18 If the second step is the rate determining step, the order of the reaction with respect to NO(g) The order of the reaction is. [JEE 2010] is : [AIEEE 2006] 10. The rate of a chemical reaction doubles for every (1) 0 (2) 1 (3) 2 (4) 3 10°C rise of temperature. If the temperature is 5. The energies of activation for forward and reverse reactions for A2 + B2 2AB are 180 kJ raised by 50°C, the rate of the reaction increases node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\02-Chemical kinetics.p65 mol–1 and 200 kJ mol–1 respectively. The presence by about :- [AIEEE-2011] of a catalyst lowers the activation energy of both (1) 32 times (2) 64 times (forward and reverse) reactions by 100 kJ mol–1. (3) 10 times (4) 24 times Th e en thalpy change o f th e reaction 11. A reactant (1) forms two products : [AIEEE-2011] (A2 + B2 ® 2AB) in the presence of catalyst will be (in kJ mol–1) - [AIEEE-2007] A ¾¾ 1 ® B, Activation Energy Ea1 k (1) 300 (2) 120 (3) 280 (4) –20 6. The half life period of a first order chemical reaction A ¾¾ k2 ® C, Activation Energy Ea2 is 6.93 minutes. The time required for the If Ea2 = 2 Ea1, then k1 and k2 are related as :- completion of 99% of the chemical reaction will be (log 2 = 0.301) :- [AIEEE-2009] (1) k1 = 2k 2 e Ea 2 / RT (2) k1 = k 2 e Ea1 / RT (1) 46.06 minutes (2) 460.6 minutes Ea1 / RT (3) k2 = k1e Ea2 / RT (4) k1 = [A] k 2 e (3) 230.3 minutes (4) 23.03 minutes 8 E  Chemical kinetics ALLEN 12. For the first order reaction [JEE 2011] 16. For the elementary reaction M ® N, the rate of 2N2O5(g) ¾® 4NO2(g) + O2(g) disappearance of M increases by a factor of 8 upon (1) the concentration of the reactant decreases exponentially with time doubling the concentration of M. The order of the (2) the half-life of the reaction decreases with reaction with respect to M is [JEE 2014] increasing temperature. (1) 4 (2) 3 (3) the half-life of the reaction depends on the initial (3) 2 (4) 1 concentration of the reactant. 17. Higher order (>3) reactions are rare due to :- (4) the reaction proceeds to 99.6% completion in eight half-life duration. [JEE-MAIN-(Offline)2015] 13. An organic compound undergoes first-order (1) shifting of equilibrium towards reactants due decomposition. The time taken for its decomposition to elastic collision to 1/8 and 1/10 of its initial concentration are (2) loss of active species on collision t1/8 and t 1/10 respectively. What is the value of (3) low probability of simultaneous collision of all the [t 1/8 ] reacting species ´ 10 ? (take log102 = 0.3) [JEE 2012] t 1/10 (4) increase in entropy and activation energy as 14. In the reaction : more molecules are involved. P + Q ¾¾ ® R+S 18. The reaction : 2N2O5(g) ® 4NO2(g) + O2(g), follows first order kinetics. The pressure of a vessel containing only N2O5 was found to increase from [Q]0 50 mm Hg to 87.5 mm Hg in 30 min. The pressure [Q] exerted by the gases after 60 min. will be (Assume temperature remains constant) [JEE-MAIN-(Online)2015] Time (1) 106.25 nm Hg (2) 116.25 nm Hg the time taken for 75% reaction of P is twice the (3) 125 mm Hg (4) 150 mm Hg time taken for 50% reaction of P. The concentration 19. For the equilibrium, A(g) ƒ B(g), DH is –40 kJ/mol. of Q varies with reaction time as shown in the figure. The overall order of the reaction is - [JEE 2013] If the ratio of the activation energies of the forward (1) 2 (2) 3 (3) 0 (4) 1 2 (Ef) and reverse (Eb) reactions is then :- 15. For the non-stoichiometric reaction 2A + B ® C + D, 3 the following kinetic data were obtained in three [JEE-MAIN-(Online)2015] separate experiments, all at 298 K. [JEE-MAIN 2014] (1) Ef = 60 kJ/mol; Eb = 100 kJ/mol (2) Ef = 30 kJ/mol; Eb = 70 kJ/mol Initial Initial Initial rate of (3) Ef = 80 kJ/mol; Eb = 120 kJ/mol node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\02-Chemical kinetics.p65 Concentration Concentration formation of C (4) Ef = 70kJ/mol; Eb = 30 kJ/mol (A) (B) (mol L–S–) 20. Decomposition of H2O2 follows a first order reaction. 0.1M 0.1M 1.2×10 –3 In fifty minutes the concentration of H2O2 decreases 0.1M 0.2M 1.2×10–3 from 0.5 to 0.125 M in one such decomposition. When the concentration of H2O2 reaches 0.05 M, 0.2M 0.1M 2.4×10–3 the rate of formation of O2 will be :- [JEE-MAIN-(Offline)2016] dc dc (1) = k[A][B]2 (2) = k[A] (1) 1.34 × 10–2 mol min–1 dt dt (2) 6.93 × 10–2 mol min–1 dc dc (3) 6.93 × 10–4 mol min–1 (3) = k[A][B] (4) = k[A]2 [B] dt dt (4) 2.66 L min–1 at STP E 9 JEE ( Main) - Chemistry ALLEN 21. The reaction of ozone with oxygen atoms in the 25. The rate of a reaction quadruples when the presence of chlorine atoms can occur by a two step temperature changes from 300 to 310 K. The process shown below : activation energy of this reaction is (Assume [JEE-MAIN-(Online)2016] activation energy and pre-exponential factor are O3(g) + Cl× (g) ® O2(g) + ClO× (g)......(i) independent of temperature ; ln 2 = 0.693, ki = 5.2 × 109 L mol–1s–1 R = 8.314 J mol–1K–1) : [MAINS-2017(online)] ClO× (g) + O× (g) ® O2(g) + Cl× (g) (1) 107.2 kJ mol–1K–1 (2) 53.6 kJ mol–1K–1 kii = 2.6 × 1010 L mol–1s–1.....(ii) (3) 214.4 kJ mol–1K–1 (4) 26.8 kJ mol–1K–1 The closest rate constant for the overall reaction 26. The rate of a reaction A doubles on increasing the O3(g) + O× (g) ® 2O2(g) is : temperature from 300 to 310 K. By how much, (1) 3.1 × 1010 L mol–1s–1 the temperature of reaction B should be increased (2) 2.6 × 1010 L mol–1s–1 from 300 K so that rate doubles if activation energy (3) 5.2 × 109 L mol–1s–1 of the reaction B is twice to that of reaction A : (4) 1.4 × 1020 L mol–1s–1 [MAINS-2017(online)] 22. the rate law for the reaction below is given by the (1) 2.45 K (2) 4.92 K expression k[A] [B] (3) 9.84 K (4) 19.67 K A + B ® Product 27. At 518° C, the rate of decomposition of a sample If the concentration of B is increased from 0.1 to of gaseous acetaldehyde, initially at a pressure of 0.3 mole, keeping the value of A at 0.1 mole, the 363 Torr, was 1.00 Torr s–1 when 5% had reacted rate constant will be : [JEE-MAIN-(Online)2016] and 0.5 Torr s–1 when 33% had reacted. The order (1) 3k (2) 9k (3) k (4) k/3 of the reaction is : [JEE-MAINS-2018(offline)] 23. According to the Arrhenius equation, (1) 3 (2) 1 (3) 0 (4) 2 [JEE 2016] 28 For a first order reaction, A ® P, t1/2 (half life) is (1) A high activation energy usually implies a fast th reaction 1 10 days. The time required for conversion of (2) Rate constant increase with increase in 4 temperature. This is due to a greater number A (in days) is :- (ln 2 = 0.693, ln 3 = 1.1) of collisions whose energy exceeds the [MAINS-2018(online)] activation energy (1) 5 (2) 4.1 (3) 3.2 (4) 2.5 (3) Higher the magnitude of activation energy, 29. N2O5 decomposes to NO2 and O2 and follows first stronger is the temperature dependence of the order kinetics. After 50 minutes, the pressure inside rate constant the vessel increases from 50 mmHg to 87.5 mmHg. (4) The pre-exponential factor is a measure of the The pressure of the gaseous mixture after rate at which collisions occur, irrespective of 100 minute at constant temperature will be: their energy. [MAINS-2018(online)] 24. Two reactions R 1 and R 2 have ide ntical (1) 116.25 mmHg (2) 175.0 mmHg pre-exponential factors. Activation energy of R 1 (3) 106.25 mmHg (4) 136.25 mmHg exceeds that of R2 by 10 kJ mol–1. If k1 and k2 are rate constants for reactions R1 and R2 respectively at 300 K, then ln(k2/k1) is equal to : (R = 8.314 J mol–1K–1) [JEE-MAINS-2017] node06\B0AI-BO\Kota\JEE(MAIN)\Booster Course Sheet\Che\Eng\Physical Chemistry\02-Chemical kinetics.p65 (1) 8 (2) 12 (3) 6 (4) 4 PREVIOUS YEARS QUESTIONS ANSWER KEY Exercise-II Que. 1 2 3 4 5 6 7 8 9 10 Ans. 1 2 1 3 4 1 1 4 0 1 Que. 11 12 13 14 15 16 17 18 19 20 Ans. 2 1,2,4 9 4 2 2 3 1 3 3 Que. 21 22 23 24 25 26 27 28 29 Ans. 3 3 2,3,4 4 1 2 4 2 3 10 E  Solution & Colligative Properties ALLEN SOLUTION & COLLIGATIVE PROPERTIES EXERCISE-I 1. The boiling point of C6H6, CH3OH, C6H5NH2 and 8. The vapour pressure of a pure liquid 'A' is 70 torr C6H 5NO 2 are 800C, 650C, 1840C and 2120C at 270C. It forms an ideal solution with another liquid respectively which will show highest vapour pressure B. The mole fraction of B is 0.2 and total vapour at room temperature : pressure of the solution is 8