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4.CHEMICAL KINETICS (1.)For the first order reaction with the rate constant k, which expression gives the rate half-life period? (Initial conc. = a) (a.) 3 2 ka 2 (b.) 1 ka (c.) 1 k (d.) 0.693 k (2.)The rate of a reaction is expressed in different ways as follows + 1 2 d[C] dt = − 1 5 d[D] dt = + 1 3 d[A] dt = − d[B] dt The reaction is (a.) 4A + B → 2C + 3D (b.) B + 5D → 3A + 2C (c.) 4A + 2B → 2C + 3D (d.) B + 1 2 D → 4A + 2C (3.)For a fist order reaction, the concentration changes from 0.8 to 0.4 in 15 min. The time taken for the concentration to change from 0.1 M to 0.025 M is (a.) 30 Min (b.) 15 Min (c.) 7.5 min (d.) 60 min (4.)For a first order reaction, A → products, the rate of reaction at [A] = 0.2 M is 1.0 × 10−2 mol L −1min−1 . The half-life period for the reaction is (a.) 476 s (b.) 496 s (c.) 832 s (d.) 242 s (5.)Half-life period of second order reaction is (a.) Proportional to initial concentration of reactants (b.) Independent of initial concentration of reactants (c.) Inversely proportional to initial concentration of reactants (d.) None of the above (6.)The half-life period for a zero order reaction is equal to (a.) 2k [A]0 (b.) [A]0 2k (c.) 0.693 k (d.) 0.693 k[A]0 (7.)A graph plotted between log k versus 1 T for calculating activation energy is shown by (a.) (b.) (c.) (d.) (8.)A reaction has a rate constant of 0.5 mol−1 dm3 min −1 . If initial concentration of the reactant is 0.2 mol dm−3 , half-life of the reaction (a.) 1.4 min (b.) 10 min (c.) 15 min (d.) 20 min (9.)The activation energies of two reactions are E1 and E2(E1 > E2). If the temperature of the system is increased from T1 to T2, the rate constant of the reactions changes from k1 to k1 in the first reaction and k2 and k2 in the second reaction. Predict which of the following expression is correct? (a.) k1 ′ k1 ′ = k2 ′ k2 ′ (b.) k1 ′ k1 ′ > k2 ′ k2 ′ (c.) k1 ′ k1 ′ < k2 ′ k2 ′ (d.) k1 ′ k1 ′ = k2 ′ k2 ′ = 1
(10.)For zero order reaction the integrated rate equation is (a.) kt = [A] [A]0 (b.) kt = [A] − [A]0 (c.) [A] = −kt + [A]0 (d.) [A] = kt − [A]0 (11.)DDT on exposure to water decomposes. Half- life is 10 yr. How much time it will take for its decomposition to 99%? (a.) 50 yr (b.) 70 yr (c.) 500 yr (d.) 700 yr (12.)What is the two third life of a first order reaction having = 5.48 × 10−14s −1 ? (a.) 2.01 × 1011s (b.) 2.01 × 1013s (c.) 8.08 × 1013s (d.) 16.04 × 1011s (13.)The minimum energy required for the reacting molecules to undergo reaction is (a.) Potential energy (b.) Kinetic energy (c.) Thermal energy (d.) Activation energy (14.)The following homogeneous gaseous reactions were experimentally found to be second order overall. 1.2NO → N2 + O2 2.3O2 → 2O3 3.N2O3 → NO + NO2 4. H2 + I2 → 2HI Which of these are most likely to be elementary reaction that occur in one step? (a.) 3 only (b.) 1 and 3 (c.) 1 and 4 (d.) 3 and 4 (15.)For a gaseous reaction, the units of rate of rate of reaction are (a.) L atm s −1 (b.) atm s −1 (c.) atm mol−1 s −1 (d.) mol s −1 (16.)1 g of 79Au198(t1/2 = 65 h) give stable mercury by β- emission. What amount of mercury will left after 260 h? (a.) 0.9375 g (b.) 0.3758 g (c.) 0.7586 g (d.) 0.9000 g (17.)............ of a reaction cannot be determined experimentally. (a.) Order (b.) Rate (c.) Rate of constant (d.) Molecularity (18.)In Arrhenius plot intercept is equal to (a.) −Ea/R (b.) ln A (c.) ln k (d.) log10 a (19.)The activation energy of a reaction is zero. The rate constant for the reaction (a.) Decreases with decrease of temp (b.) Increases with increase of temp (c.) Decreases with increase of temp (d.) Is nearly independent of temp (20.)The rate constant for a chemical reaction has units L mol −1 s −1 ,order of the reaction will be (a.) 0 (b.) 1 (c.) 2 (d.) 3 (21.)For the reaction, N2 + 3H2 ⇌ 2NH3 the rate of change of concentration for hydrogen is −0.3 × 10−4 Ms−1 . The rate of change of concentration of ammonia is (a.) −0.2 × 10−4 (b.) 0.2 × 10−4 (c.) 0.1 × 10−4 (d.) 0.3 × 10−4 (22.)Rate of reaction (a.) Decreases with increase in temperature (b.) Increases with increase in temperature (c.) May increase or decrease with increase in temperature (d.) Does not depends on temperature (23.)For the reaction,Cl2 + 2l − → I2 + 2Cl −,the initial concentration of I − was 0.20 mol L −1 and the concentration after 20 min was 0.20 mol L −1 .Then the rate of formation of I2 in mol L −1 would be (a.) 1 × 10−4 (b.) 5 × 10−4 (c.) 1 × 10−3 (d.) 5 × 10−3 (24.)A chemical reaction proceeds following formula k = PZe −Ea/RT Which of the following process will increase the rate of reaction? (a.) Lowering of Ea (b.) Lowering of P (c.) Lowering of Z (d.) Independent of all the above factors (25.)A reaction was observed for 15 days and the percentage of the reactant remaining after the days indicated was recorded in the following table. Time (days) % Reactant remaining
0 100 2 50 4 39 6 25 8 21 10 18 12 15 14 12.5 15 10 Which one of following best describes the order and the half-life of the reaction? Reaction order Half-life (days) (a.) First 2 (b.) First 6 (c.) Second 2 (d.) Zero 6 (26.)For reaction A → B, the rate constant k1 = A1e −Ea1/RT and for the reaction X → Y, the rate constant k2 = A2e −Ea2/RT . If A1 = 108 ,A2 = 1010 and Ea1 = 600 cal/mol, Ea2 = 1800 cal/ mol, then the temperature at which k1 = k2 is (R = 2 cal/k mol) (a.) 200 3.506 K (b.) 300 2.303 K (c.) 400 6.506 K (d.) 200 5.204 K (27.)For a reaction between A and B, the initial rate of reaction is measured for various initial concentrations A and B. the data provided are [A] [B] Initial reaction rate 1 0.20 M 0.30 M 5 × 10−5 2 0.20 M 0.10 M 5 × 10−5 3 0.40 M 0.05 M 1 × 10−5 The overall order of the reaction is (a.) One (b.) Two (c.) Two and half (d.) Three (28.)The rate of a chemical reaction doubles for every 10°C rise of temperature. If the temperature is raised by 50°C, the rate of the reaction increases by about (a.) 10 times (b.) 24 times (c.) 32 times (d.) 64 times (29.)The units of the rate constant of a second order reaction are (a.) mol −1L −1 s −1 (b.) mol −1Ls −1 (c.) mol −1Ls (d.) mol L −1 s −1 (30.)In the respect of the equation k = Ae −Ea/RTin chemical kinetics, which one of the following statements is correct? (a.) K is equilibrium constant (b.) A is adsorption factor (c.) Ea is energy of activation (d.) R is Rydberg constant (31.)The rate law for a reaction between the substances A and B is given by rate = k[A] n[B]m . On doubling the concentration of A and halving the concentration of B, the ratio of the new rate to the earlier rate of the reaction will be as (a.) 1 2m+n (b.) (m + n) (c.) (n − m) (d.) 2 (n−m) (32.)In the following reaction A → B + C, rate constant is 0.001 Ms−1 . Half-life and completion time of the given reaction are (a.) 500 s, 1000 s (b.) 500 s, 750 s (c.) 250 s, 500 s (d.) 300 s, 600 s (33.)For a reaction of the type A + B → x products, it is observed that doubling the concentration of A causes the reaction rate (k1 ) to be four times as great but doubling the amount of B does not affect the rate (k2 ). The rate equation is (a.) k = k1 + k2 (b.) k = k1k2 (c.) k = k1 k2 (d.) k 1/2 = k1 × k2 (34.)Which one of the following statement for order of reaction is not correct ? (a.) Order can be determined experimentally (b.) Order of reaction is equal to sum of the power of concentration terms in differential rate law (c.) It is not affected with stoichiometric coefficients of the reactants (d.) Order cannot be fractional (35.)A reactant (A) forms two products : A k2 → B, Activation energy Ea1 A k2 → C, Activation energy Ea2 If Ea2 = 2 Ea1 , than k1 and k2 are related as (a.) k1 = 2k2eEa2 /RT (b.) k1 = k2eEa1 /RT (c.) k2 = k1eEa2 /RT (d.) k1 = Ak2eEa1 /RT (36.)If X is the total number of collisions which a gas molecule register with others per unit time under
particular conditions, then the collision frequency of the gas containing N molecules per unit volume is (a.) X/N (b.) NX (c.) 2 NX (d.) NX/2 (37.)The rate constant of a first order reaction is 3 × 10−6 per second and initial concentration is 0.10 M. Then the initial rate of reaction is (a.) 3 × 10−6ms −1 (b.) 3 × 10−8ms −1 (c.) 3 × 10−7ms −1 (d.) 3 × 10−9ms −1 (38.)For the chemical change A → B it is found that the rate of reaction doubles when the concentration is increased by 4 times. The order of the reaction is (a.) One (b.) Two (c.) Half (d.) None of these (39.)For the reaction, 2N2O5 (g) → 4NO2 (g) + O2(g) If the concentration of NO2 increase by 5.2 × 10−3M in 100 s then the rate of the reactions (a.) 1.3 × 10−5Ms −1 (b.) 0.5 × 10−4Ms −1 (c.) 7.6 × 10−4Ms −1 (d.) 2 × 10−3Ms −1 (40.)The concentration of a reactant X decreases from 01 M to 0.005 m in 40 min. If the reaction follows first order kinetics, the rate of the reaction when the concentration of X is 0.01 M will be (a.) 1.73 × 10−4Mmin −1 (b.) 3.47 × 10−4Mmin −1 (c.) 3.47 × 10−5M min −1 (d.) 7.5 × 10−4M min −1 (41.)Give the hypothetical reaction mechanism A I → B II → C III → D IV → E and the date as Species formed Rate of its Formation B 0.002 mol/h, per mole of A C 0.030 mol/h, per mole of B D 0.011 mol/h, per mole of C E 0.420 mol/h, per mole of D The rate determining step is (a.) Step I (b.) Step II (c.) Step III (d.) Step IV (42.)According to the Arrhenius equation a straight line is to be obtained by plotting the logarithm of the rate constant of a chemical reaction (log k) against (a.) T (b.) log T (c.) 1 T (d.) log 1 T (43.)Consider following two reaction, A → product − d[A] dt = k1 [A] 0 B → product − d[B] dt = k2 [B] 0 k1and k2 are expressed in term of molarity (mol L −1 ) and time (s −1 ) as (a.) s −1 , M s −1L −1 (b.) Ms−1 , M s −1 (c.) s −1 , M−1 s −1 (d.) Ms−1 , L s −1 (44.)Find the two third life (t1/2)of a first order reaction in which k = 5.48 × 10−14per second (a.) 201 × 1013s (b.) 2.01 × 1013s (c.) 201 × 1020s (d.) 0.201 × 1010s (45.)Plots showing the variation of the rate constant (k) with temperature (T) are given below. The plot that follows Arrhenius equation is (a.) (b.) (c.) (d.) (46.)The rate constant of a first order reaction whose half-life is 480 s is (a.) 1.44 s −1 (b.) 1.44 × 10−3 s −1