MCQOPTIONS
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MCQOPTIONS
This section includes 15 Mcqs, each offering curated multiple-choice questions to sharpen your Chemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A first-order reaction is 50 percent complete in 30 minutes. Calculate the time taken for completion of 87.5 percent of the reaction. |
| A. | 30 minutes |
| B. | 60 minutes |
| C. | 90 minutes |
| D. | 120 minutes |
| Answer» D. 120 minutes | |
| 2. |
What is the time required for 75 percent completion of a first-order reaction? |
| A. | 3 t<sub>50</sub> |
| B. | 4 t<sub>50</sub> |
| C. | 4.5 t<sub>50</sub> |
| D. | 2 t<sub>50</sub> |
| Answer» E. | |
| 3. |
For the reaction X Y + Z, the rate constant is 0.00058 s-1. What percentage of X will be decomposed in 50 minutes? |
| A. | 90.02 percent |
| B. | 82.44 percent |
| C. | 88.82 percent |
| D. | 82.67 percent |
| Answer» C. 88.82 percent | |
| 4. |
What is the time taken to complete 75 percent of the reaction if the rate of the first-order reaction is 0.023 min-1? |
| A. | 60.28 minutes |
| B. | 69.28 minutes |
| C. | 50.37 minutes |
| D. | 65.97 minutes |
| Answer» B. 69.28 minutes | |
| 5. |
A first-order reaction was 70 percent complete in 20 minutes. What is the rate constant of the reaction? |
| A. | 0.07 min<sup>-1</sup> |
| B. | 0.06 min<sup>-1</sup> |
| C. | 0.08 min<sup>-1</sup> |
| D. | 0.09 min<sup>-1</sup> |
| Answer» C. 0.08 min<sup>-1</sup> | |
| 6. |
The half-life of a given reaction is doubled if the initial concentration of the reactant is doubled. What is the order of the reaction? |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» B. 1 | |
| 7. |
The unit of the rate constant of a zero-order reaction and second-order reaction is same. |
| A. | True |
| B. | False |
| Answer» C. | |
| 8. |
The unit of rate constant of a first-order reaction is s-1. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9. |
What is the formula to calculate the time taken for the completion of a zero-order reaction? |
| A. | t<sub>100%</sub> = [A]<sub>0</sub>/k |
| B. | t<sub>100%</sub> = [A]<sub>0</sub>/2k |
| C. | t<sub>100%</sub> = 2[A]<sub>0</sub>/k |
| D. | t<sub>100%</sub> = [A]<sub>0</sub>/3k |
| Answer» B. t<sub>100%</sub> = [A]<sub>0</sub>/2k | |
| 10. |
The decomposition of N2O5 in CCl4 solution was studied. N2O5 2NO2 + 1/2O2. The rate constant of the reaction is 6.2 x 10-4 sec-1. Calculate the rate when the concentration of N2O5 is 1.25 molar. |
| A. | 6.45 x 10<sup>-4</sup> |
| B. | 7.45 x 10<sup>-4</sup> |
| C. | 6.75 x 10<sup>-4</sup> |
| D. | 7.75 x 10<sup>-4</sup> |
| Answer» E. | |
| 11. |
For a certain reaction the values of Arrhenius factor and Activation energy are 4 x 1013 collision/sec and 98.6KJ/mol at 303K. Calculate the rate constant if reaction is 1st order?( R=8.341mol-1K-1) |
| A. | 6.07 x 10<sup>-3</sup> |
| B. | 3.02 x 10<sup>-5</sup> |
| C. | 4.07 x 10<sup>-4</sup> |
| D. | 7.42 x 10<sup>-3</sup> |
| Answer» D. 7.42 x 10<sup>-3</sup> | |
| 12. |
What is the integrated rate equation for a first order reaction? |
| A. | [A] = [A]<sub>0</sub>e<sup>-kt</sup> |
| B. | [A] = [A]<sub>0</sub>/e<sup>-kt</sup> |
| C. | [A] = [A]<sub>0</sub>e<sup>-t</sup> |
| D. | [A] = [A]<sub>0</sub>e<sup>-k</sup> |
| Answer» B. [A] = [A]<sub>0</sub>/e<sup>-kt</sup> | |
| 13. |
A zero-order reaction is 25% complete in 30seconds. What time does it take for 50% completion? |
| A. | 40s |
| B. | 70s |
| C. | 50s |
| D. | 60s |
| Answer» E. | |
| 14. |
What time does it take for reactants to reduce to 3/4 of initial concentration if the rate constant is 7.5 x 10-3 s-1? |
| A. | 38.4s |
| B. | 40.2s |
| C. | 39.3s |
| D. | 36.8s |
| Answer» B. 40.2s | |
| 15. |
The rate constant of a reaction is 0.01s-1, how much time does it take for 2.4 mol L-1 concentration of reactant reduced to 0.3 mol L-1? |
| A. | 108.3s<sup>-1</sup> |
| B. | 207.9s<sup>-1</sup> |
| C. | 248.2s<sup>-1</sup> |
| D. | 164.8s<sup>-1</sup> |
| Answer» C. 248.2s<sup>-1</sup> | |