MCQOPTIONS
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MCQOPTIONS
This section includes 82 Mcqs, each offering curated multiple-choice questions to sharpen your Chemistry knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
The reactions catalyzed by sunlight are called reactions |
| A. | Exothermic |
| B. | None of these |
| C. | Photochemical |
| D. | Endothermic |
| Answer» D. Endothermic | |
| 52. |
in a reaction: 2A→B + 2C, which of the statement is true? |
| A. | Rate of formation of B = Rate of disappearance of A |
| B. | Rate of disappearance of A=Rate of formation of C |
| C. | Rate of formation of C= Rate of formation of B |
| D. | None of these |
| Answer» B. Rate of disappearance of A=Rate of formation of C | |
| 53. |
The reactions with the high value of energy of activation are? |
| A. | Moderate |
| B. | Fast |
| C. | Slow |
| D. | None of these |
| Answer» D. None of these | |
| 54. |
Rusting of iron Is an example of________ reaction |
| A. | none of these |
| B. | slow |
| C. | Moderate |
| D. | Fast |
| Answer» C. Moderate | |
| 55. |
Powdered marble reacts more rapidly with HCL than the chips of marble because: |
| A. | Energy of activation decreases |
| B. | None of these |
| C. | Number of molecules increases. |
| D. | Surface area of powdered marble is more that of chips of marble and hence there is more collisions between the molecules of reactants |
| Answer» E. | |
| 56. |
Which of the following are best to explain the action of negative catalyst in a chemical reaction? |
| A. | It decreases the rate of reaction because rate constant for the reaction increases. |
| B. | It decreases the rate of the reaction because smaller fraction of the total molecules will react due to increase of energy activation. |
| C. | None of These |
| D. | It decreases the rate constant because the adding catalyst recovered unchanged at the end of the reaction |
| Answer» C. None of These | |
| 57. |
The reaction A + B -> products is found to be second order in [A] and first order in [B]. The rate equation would be: |
| A. | R = k[A]2[B] |
| B. | R = k[A][B]2 |
| C. | R = k[B] |
| D. | R = k[A][B] |
| Answer» B. R = k[A][B]2 | |
| 58. |
For a certain first order reaction, it is found that it takes 156 seconds for the concentration of reactant to fall from 0.100 M to 0.0500 M. How much time would it take for the concentration of reactant to fall from 0.0500 M to 0.0250 M? |
| A. | 156 |
| B. | 76 |
| C. | 15 |
| D. | 312 |
| Answer» B. 76 | |
| 59. |
The term — dx/dt in the rate expression refers to the? |
| A. | instantaneous rate of the reaction |
| B. | Average rate of the reaction |
| C. | increase in concentration of the reactants |
| D. | Change in concentration of. the reactants with time |
| Answer» E. | |
| 60. |
Which of the following would NOT increase the rate of reaction |
| A. | adding a catalyst |
| B. | increasing the concentration of reactants |
| C. | raising the temperature |
| D. | increasing the volume of the container for a gaseous reaction. |
| Answer» E. | |
| 61. |
For a certain reaction, it is found that the equation relating the specific rate constant, k(M/s), and absolute temperature, T, is: lnk = -4420/T + 120. What is the value of the specific rate constant, k(M/s) at 500 K? |
| A. | 28.8 |
| B. | 204 |
| C. | 36 |
| D. | 10.4 |
| Answer» B. 204 | |
| 62. |
What is the activation energy, in kJ/mole, for the process described in problem 9? |
| A. | -36.7 |
| B. | 36.7 |
| C. | -42 |
| D. | 42 |
| Answer» C. -42 | |
| 63. |
Which of the following compound is depleting the ozone umbrella? |
| A. | Bromomethane |
| B. | Chloroform |
| C. | chlorofluorocarbons |
| D. | None |
| Answer» D. None | |
| 64. |
For a certain reaction, it is found that the rate equation is R = 0.015 L/mol·s[A][B] Calculate the rate of the reaction, in mol/L·s, when [A] = 0.022 M and [B] = 0.055 M. |
| A. | 0 x 10-6 |
| B. | 0 x 10-7 |
| C. | 5 x 10-2 |
| D. | 8 x 10-5 |
| Answer» B. 0 x 10-7 | |
| 65. |
A 000 g sample of live grass gives 116 decays per hour of carbon-1 A 000 g sample of grass found in an Egyptian tomb gives 34 decays per hour. The half-life of carbon-14 is 5720 years. How old, in years, is the ancient grass? |
| A. | 19500 |
| B. | 1680 |
| C. | 10100 |
| D. | 7020 |
| Answer» D. 7020 | |
| 66. |
For the reaction 2A + 3B + C = Products, the rate equation is |
| A. | R = k[A]2[B]3[C] |
| B. | R = k[A][B][C] |
| C. | R = k[A]2 |
| D. | Insufficient information to fix rate equation |
| Answer» E. | |
| 67. |
A reaction involving two different reactants can never be |
| A. | Bimolecular reaction |
| B. | First order reaction |
| C. | Second order reaction |
| D. | Unimolecular reaction |
| Answer» E. | |
| 68. |
The rate of reaction between two reactants A and B decreases by a factor of 4 if the concentration of reactant B is doubled. The order of reaction with respect to reactant B is |
| A. | -2 |
| B. | 2 |
| C. | -1 |
| D. | 1 |
| Answer» B. 2 | |
| 69. |
Which of the following statements for order of reaction is not correct? |
| A. | It is not affected with the stoichiometric coefficients of the reactants |
| B. | Order of a reaction is equal to the sum of the power of concentration terms in differential rate law |
| C. | Order can be determined experimentally |
| D. | Order cannot be fractional |
| Answer» E. | |
| 70. |
The time taken for 10% completion of a first order reaction is 20 min. Then, for 19% completion, the reaction will take |
| A. | 50 mins |
| B. | 60 mins |
| C. | 40 mins |
| D. | 30 mins |
| Answer» D. 30 mins | |
| 71. |
Consider an endothermic reaction, X → Y with activation energies Eb and Ef respectively for the backward and forward reactions, respectively. In general, |
| A. | there is no definite relation between Eb and Ef |
| B. | Eb > Ef |
| C. | Eb < Ef |
| D. | Eb = Ef |
| Answer» D. Eb = Ef | |
| 72. |
In a first order reaction, the concentration of the reactant decreases from 0.8 M to 0.4 M in 15 minutes. 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 |
| Answer» B. 15 min | |
| 73. |
The half life period of a first order chemical reaction is 6.93 minutes. The time required for the completion of 99% of the chemical reaction will be (log 2 = 0.301) |
| A. | 46.06 minutes |
| B. | 230.3 minutes |
| C. | 203 minutes |
| D. | 460.6 minutes |
| Answer» B. 230.3 minutes | |
| 74. |
The reaction: A → B follows first order kinetics. The time taken for 0.8 mol of A to produce 0.6 mol of B is 1 hour. What is the time taken for conversion of 0.9 mol of A to produce 0.675 mol of B? |
| A. | 0.5 hour |
| B. | 2 hour |
| C. | 0.25 hour |
| D. | 1 hour |
| Answer» E. | |
| 75. |
For the reaction A + B → products, it is observed that (i) On doubling the concentration of A only, the rate of reaction is also doubled. (ii) On doubling the initial concentration of both A and B, there is change by a factor of 8 in the rate of reaction. The rate of reaction is given by |
| A. | rate = k [A] [B] |
| B. | rate = k [A] [B]2 |
| C. | rate = k [A]2 [B] |
| D. | rate = k [A]2 [B]2 |
| Answer» C. rate = k [A]2 [B] | |
| 76. |
t1/4 can be taken as the time taken for the concentration of a reactant to drop to 3/4 of its initial value. If rate constant for a first order reaction is k, then t1/4 can be written as |
| A. | 0.01/k |
| B. | 0.69/k |
| C. | 0.29/k |
| D. | 0.75/k |
| Answer» D. 0.75/k | |
| 77. |
The number of collisions depend upon |
| A. | Pressure |
| B. | Concentration |
| C. | Temperature |
| D. | All the above |
| Answer» E. | |
| 78. |
Temperature dependent equation can be written as [Orrisa JEE 2005] |
| A. | \[\ln \,k=\ln A-{{e}^{{{E}_{a}}/RT}}\] |
| B. | \[\ln k=\ln A+{{e}^{{{E}_{a}}/RT}}\] |
| C. | \[\ln k=\ln A-{{e}^{RT/{{E}_{a}}}}\] |
| D. | All of these |
| Answer» B. \[\ln k=\ln A+{{e}^{{{E}_{a}}/RT}}\] | |
| 79. |
The Arrhenius equation expressing the effect of temperature on the rate constant of a reaction is [MP PET 1997] |
| A. | \[k={{e}^{-{{E}_{a}}/RT}}\] |
| B. | \[k={{E}_{a}}/RT\] |
| C. | \[k={{\log }_{e}}\,\frac{{{E}_{a}}}{RT}\] |
| D. | \[k=A{{e}^{-{{E}_{a}}/RT}}\] |
| Answer» E. | |
| 80. |
Which of the following statements is not true according to collision theory of reaction rates |
| A. | Collision of molecules is a precondition for any reaction to occur |
| B. | All collisions result in the formation of the products |
| C. | Only activated collisions result in the formation of the products |
| D. | Molecules which have acquired the energy of activation can collide effectively |
| Answer» C. Only activated collisions result in the formation of the products | |
| 81. |
The energy of activation is |
| A. | The energy associated with the activated molecules |
| B. | Threshold energy ?energy of normal molecules |
| C. | Threshold energy + energy of normal molecules |
| D. | Energy of products ?energy of reactants |
| Answer» C. Threshold energy + energy of normal molecules | |
| 82. |
Activation energy is |
| A. | The amount of energy to be added to the actual energy of a molecule so that the threshold energy is reached |
| B. | The amount of energy the molecule must containso that it reacts |
| C. | The energy which a molecule should have in order to enter into an effective collision |
| D. | The average kinetic energy of the molecule |
| Answer» B. The amount of energy the molecule must containso that it reacts | |