Free NEET Chemistry multiple-choice questions on Rate of Reaction. Attempt each question and reveal the answer with a full explanation.
For the reaction 2A + B 3C + D , which of the following expressions does not correctly represent the rate of the reaction? - d[B] 2dt - d[A] 2dt - d[B] dt d[D] dt The reaction A + B Products is first-order with respect to A and zero-order with respect to B . If B is taken in large excess, the reaction is known as a: Pseudo-first-order reaction Zero-order reaction Second-order reaction Trimolecular reaction In collision theory, the probability factor P is also known as: Steric factor Boltzmann factor Frequency factor Activation factor For the reaction N 2(g) + 3H 2(g) 2NH 3(g) , the relation between the rate of disappearance of H 2 and the rate of appearance of NH 3 is: - 1 3 d[H 2] dt = 1 2 d[NH 3] dt - d[H 2] dt = d[NH 3] dt - d[H 2] dt = 2 3 d[NH 3] dt - d[H 2] dt = 3 2 d[NH 3] dt The unit of rate constant for a zero-order reaction is: mol L -1 s -1 L mol -1 s -1 s -1 L 2 mol -2 s -1 Acid-catalyzed hydrolysis of ethyl acetate is a: Pseudo-first order reaction Second order reaction Zero order reaction Third order reaction For a gaseous reaction, the rate is expressed in terms of dP/dt instead of dc/dt or dn/dt . The unit of rate will be: atm s -1 mol L -1 s -1 atm -1 s -1 mol s -1 The reaction H 2(g) + Cl 2(g) hv 2HCl(g) is an example of: Zero-order reaction First-order reaction Second-order reaction Third-order reaction In a pseudo-first-order reaction, such as the hydrolysis of cane sugar, the concentration of water is not included in the rate law because: It is present in large excess and its concentration remains practically constant It does not participate in the reaction It acts as a catalyst It is a product of the reaction For a reaction of the type 2A + B 2C , the rate of disappearance of A is 2.6 10 -2 mol L -1 s -1 . The rate of appearance of C is: 2.6 10 -2 mol L -1 s -1 1.3 10 -2 mol L -1 s -1 5.2 10 -2 mol L -1 s -1 2.6 10 -4 mol L -1 s -1 In a hypothetical reaction A + B C , the activation energy is E a . If the reaction is carried out in the presence of a catalyst, which quantity remains unchanged? Enthalpy of reaction ( ΔH ) Activation energy Rate constant Rate of reaction Which of the following describes the 'molecularity' of a reaction correctly? It is the number of reactant species taking part in an elementary reaction. It can be zero or a fraction. It is determined experimentally. It applies to complex (multi-step) reactions as well. Which of the following units represents the rate of reaction? mol L -1 s -1 mol -1 L s -1 mol L s -1 s -1 Which of the following is an example of a pseudo-first-order reaction? Hydrolysis of sucrose in the presence of acid Decomposition of N 2O 5 Thermal decomposition of HI on gold surface Reaction between H 2 and Cl 2 in sunlight In the Maxwell-Boltzmann distribution, what does the area under the curve represent? Total number of molecules Total energy of the system Activation energy Average velocity For the reaction H 2 + I 2 → 2HI , the rate expression is given by Rate = k[H 2][I 2] . If I 2 is present in large excess, the reaction follows: Pseudo-first order kinetics Second order kinetics Zero order kinetics Third order kinetics Which of the following describes a 'complex reaction'? A reaction that proceeds in a series of elementary steps A reaction with a molecularity greater than three A reaction that occurs in a single step A reaction where the order and molecularity are always the same Which of the following statements about the 'Rate Determining Step' is correct? It is the slowest step in a multi-step reaction It is the fastest step in a multi-step reaction It always involves the reaction of the final products It has the lowest activation energy In a zero-order reaction, the time required for the concentration to change from 0.5 M to 0.2 M is 30 seconds. The rate constant is: 0.01 mol L -1 s -1 0.03 mol L -1 s -1 0.3 mol L -1 s -1 0.1 mol L -1 s -1 The reaction A + B C + D occurs in a single step. The molecularity of this reaction is: 2 1 0 3 For the reaction : 2A + B -> 3C + D Which of the following does not express the reaction rate:- - d[C] 3dt - d[B] dt d[D] dt - d[A] 2dt Consider the reaction N2(g) + 3H2(g) -> 2NH3(g) The equality relationship between d[NH 3] dt and - d[H 2] dt is :- d[NH 3] dt =- 1 3 d[H 2] dt d[NH 3] dt =- 2 3 d[H 2] dt d[NH 3] dt =- 3 2 d[H 2] dt d[NH 3] dt =- d[H 2] dt What is the effect of a catalyst on the Gibbs free energy change ( G ) of a reaction? It has no effect on G It decreases G It increases G It makes G zero For the reaction, N2 + 3H2 -> 2NH3 , If d[ NH3 ] dt =2 10 -4 mol L -1 s -1 , The value of -d[ H2 ] dt would be - 1 10 -4 mol L -1 s -1 3 10 -4 mol L -1 s -1 4 10 -4 mol L -1 s -1 6 10 -4 mol L -1 s -1 In the reaction BrO3 - (aq) + 5Br - (aq) + 6H + -> 3Br2(l) + 3H2O(l) The rate of appearance of bromine ( Br 2 ) is related to rate of disappearance of bromide ions as following d ( Br 2 ) dt = 3 5 d ( Br - ) dt d ( Br 2 ) dt = - 3 5 d ( Br - ) dt d ( Br 2 ) dt = - 5 3 d ( Br - ) dt d ( Br 2 ) dt = 5 3 d ( Br - ) dt For the chemical reaction N2(g) + 3H2(g) <=> 2NH3(g) The correct option is: 3 d[ H2 ] dt = 2 d[ NH3 ] dt - 1 3 d[ H2 ] dt = - 1 2 d[ NH3 ] dt - d[ N2 ] dt = 2 d[ NH3 ] dt - d[ N2 ] dt = 1 2 d[ NH3 ] dt An increase in the concentration of the reactants of a reaction leads to change in heat of reaction threshold energy collision frequency activation energy Which one is an example of heterogenous catalysis? Oxidation of sulphur dioxide into sulphur trioxide in the presence of oxides of nitrogen Hydrolysis of sugar catalysed by H+ ions Decomposition of ozone in presence of nitrogen monoxide Combination between dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron The decomposition of phosphine ( PH 3 ) on tungsten at low pressure is a first-order reaction. It is because the: rate is proportional to the surface coverage rate is inversely proportional to the surface coverage rate is independent of the surface coverage rate of decomposition is very slow For a reaction 3A 2B , the rate of reaction + d[B] dt is equal to: - 2 3 d[A] dt - 3 2 d[A] dt - d[A] dt - 1 3 d[A] dt For a reaction A + 2B C , the rate law is Rate = k[A][B] . What is the molecularity of the reaction? 3 2 1 0 For a reaction 2A + B 3C , if the rate of formation of C is 0.06 mol L -1 s -1 , the rate of disappearance of A is: 0.04 mol L -1 s -1 0.06 mol L -1 s -1 0.09 mol L -1 s -1 0.02 mol L -1 s -1 If a catalyst is added to a reaction, the value of the equilibrium constant ( K eq ): Remains unchanged Increases Decreases Becomes zero The collision frequency Z depends on temperature T as: Z ∝ ∑T Z ∝ T Z ∝ T 2 Z ∝ e -T The decomposition of phosphine ( PH 3 ) on a hot tungsten surface at very high pressure is: Zero-order First-order Second-order Fractional-order For the reaction A + 3B 2C , the rate of disappearance of B is 6 10 -3 mol L -1 s -1 . The rate of formation of C is: 4 10 -3 mol L -1 s -1 9 10 -3 mol L -1 s -1 2 10 -3 mol L -1 s -1 6 10 -3 mol L -1 s -1 The steric factor ( P ) is introduced in the collision theory to account for: The orientation of colliding molecules The energy of colliding molecules The frequency of collisions The temperature of the reaction For the reaction 4NH 3(g) + 5O 2(g) 4NO(g) + 6H 2O(g) , the rate of reaction in terms of disappearance of NH 3 is - d[NH 3] dt . What is the correct relationship to the rate of appearance of H 2O ? 1 4 d[NH 3] dt = - 1 6 d[H 2O] dt d[NH 3] dt = d[H 2O] dt -6 d[NH 3] dt = 4 d[H 2O] dt -4 d[NH 3] dt = 6 d[H 2O] dt The rate of a gaseous reaction is given by r = k[A][B] . If the volume of the reaction vessel is suddenly reduced to 1/4 th of the initial volume, the rate of reaction relative to the original rate r will be: 16r 8r 4r r/16 In the reaction A + 2B 3C , the rate of appearance of C at time t is 1.2 10 -2 mol L -1 s -1 . The rate of disappearance of B at that time is: 0.8 10 -2 mol L -1 s -1 1.2 10 -2 mol L -1 s -1 1.8 10 -2 mol L -1 s -1 0.4 10 -2 mol L -1 s -1 For the reaction 2N 2O 5(g) → 4NO 2(g) + O 2(g) , the rate of formation of NO 2 is 2.8 10 -3 mol ∙ L -1 s -1 . The rate of disappearance of N 2O 5 is: 1.4 10 -3 mol ∙ L -1 s -1 2.8 10 -3 mol ∙ L -1 s -1 5.6 10 -3 mol ∙ L -1 s -1 0.7 10 -3 mol ∙ L -1 s -1 The reaction A + 2B → C is an elementary reaction. If the volume of the reaction vessel is tripled, the rate of reaction will: Decrease to 1/27 of the original rate Increase to 27 times the original rate Decrease to 1/9 of the original rate Remain unchanged For the reaction 5Br -(aq) + BrO 3 -(aq) + 6H +(aq) 3Br 2(aq) + 3H 2O(l) , if the rate of disappearance of Br - is x mol L -1 s -1 , the rate of appearance of Br 2 is: 3 5 x 5 3 x x 3 x 5 The reaction 2NO(g) + O 2(g) 2NO 2(g) is an elementary reaction. If the volume of the reaction vessel is halved, the rate of the reaction will: Increase by 8 times Increase by 4 times Decrease by 8 times Remain the same What is the molecularity of the reaction Cl 1 2 Cl 2 ? Unimolecular Bimolecular Trimolecular Zero For the reaction 2A + B 3C , the rate of formation of C is 1.2 10 -2 mol L -1 s -1 . What is the rate of disappearance of A ? 0.8 10 -2 mol L -1 s -1 1.8 10 -2 mol L -1 s -1 2.4 10 -2 mol L -1 s -1 0.4 10 -2 mol L -1 s -1 For the reaction 2A + 3B 4C , if the rate of disappearance of A is r A , the rate of appearance of C ( r C ) is related to r A by: r C = 2r A r C = 1 2 r A r C = 4 3 r A r C = 3 2 r A For the reaction H 2 + Cl 2 2HCl occurring over water, the rate of reaction is found to be independent of the pressure of H 2 and Cl 2 . The order of the reaction is: 0 1 2 0.5 The term 'Effective Collisions' in collision theory refers to collisions that possess: Both proper orientation and threshold energy Only threshold energy Only proper orientation High frequency of collision Which of the following is an example of a zero-order reaction under specific conditions? Decomposition of NH 3 on a hot Pt surface at high pressure Hydrolysis of ethyl acetate in acidic medium Decomposition of N 2O 5 in CCl 4 Inversion of cane sugar A reaction with molecularity 3 is rare compared to molecularity 1 or 2 because: The probability of three molecules colliding simultaneously in correct orientation is very low. Trimolecular reactions are always endothermic. Trimolecular reactions require high pressure. Activation energy for such reactions is always zero. For the reaction 2H 2O 2 2H 2O + O 2 , the rate of disappearance of H 2O 2 is 6.8 10 -4 mol L -1 s -1 . What is the rate of appearance of O 2 ? 3.4 10 -4 mol L -1 s -1 6.8 10 -4 mol L -1 s -1 1.36 10 -3 mol L -1 s -1 1.7 10 -4 mol L -1 s -1 For the reaction, XA + YB -> ZC , if - d[A] dt = - d[B] dt = 1.5 d[C] dt , then the correct statement among the following is The value of Y = 2 The value of X = Y = Z = 3 The value of X = Y = 3 The value of X = 2 In the reaction A(g) 2B(g) + C(g) , the total pressure increases while the volume is constant. If the initial pressure is P i and the total pressure at time t is P t , what is the partial pressure of A ( P A ) at time t ? (3P i - P t)/2 (2P i - P t) P t - P i (P i + P t)/2 In a multistep reaction, the overall rate of the reaction is governed by: The slowest step The fastest step The average of all steps The first step What happens to the rate constant k of a reaction when the concentration of the reactants is doubled at a constant temperature? It remains unchanged It is doubled It is quadrupled It is halved The hydrolysis of ethyl acetate in acidic medium is an example of: Pseudo-first order reaction Zero order reaction Second order reaction Third order reaction If the volume of a reaction vessel containing the gas phase reaction 2A(g) B(g) is halved, the rate of reaction will: Increase by 4 times Increase by 2 times Decrease by 4 times Remain unchanged