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MCQOPTIONS
This section includes 1187 Mcqs, each offering curated multiple-choice questions to sharpen your NEET knowledge and support exam preparation. Choose a topic below to get started.
| 551. |
The activation energy for a reaction which doubles the rate when the temperature is raised from 298 K to 308 K is |
| A. | \[59.2\text{ }kJ\,mo{{l}^{-1}}\] |
| B. | \[39.2\text{ kJ }mo{{l}^{-1}}\] |
| C. | \[52.9\,kJ\,mo{{l}^{-1}}\] |
| D. | \[29.5\,kJ\,mo{{l}^{-1}}\] |
| Answer» D. \[29.5\,kJ\,mo{{l}^{-1}}\] | |
| 552. |
The reaction \[X\to Y\] is an exothermic reaction. Activation energy of the reaction for X into Y is\[150\,kJ\,mo{{l}^{-1}}\]. Enthalpy of reaction is\[135\text{ }k\,J\,mo{{l}^{-1}}\]. The activation energy for the reverse reaction, \[Y\to X\] will be: |
| A. | \[280\,kJ\,mo{{l}^{-1}}\] |
| B. | \[285\text{ }kJmo{{l}^{-1}}\] |
| C. | \[270\text{ }kJ\,mo{{l}^{-1}}\] |
| D. | \[15\,kJ\,mo{{l}^{-1}}\] |
| Answer» C. \[270\text{ }kJ\,mo{{l}^{-1}}\] | |
| 553. |
The rate coefficient (K) for a particular reactions is \[1.3\times {{10}^{-4}}{{M}^{-1}}{{s}^{-1}}\] at\[100{}^\circ C\], and \[1.3\times {{10}^{-3}}{{M}^{-1}}{{s}^{-1}}\] at\[150{}^\circ C\]. What is the energy of activation \[\left( {{E}_{a}} \right)\] (in kJ) for this reaction? (R = molar gas constant\[=8.314\text{ }J{{K}^{-1}}mo{{l}^{-1}}\]) |
| A. | 16 |
| B. | 60 |
| C. | 99 |
| D. | 132 |
| Answer» C. 99 | |
| 554. |
For the exothermic reaction \[A+B\to C+D,\text{ }\Delta H\]is the heat of reaction and \[{{E}_{a}}\]is the energy of activation. The energy of activation for the formation of A + B will be |
| A. | \[{{E}_{a}}\] |
| B. | \[\Delta H\] |
| C. | \[{{E}_{a}}+\Delta H\] |
| D. | \[\Delta H-{{E}_{a}}\] |
| Answer» D. \[\Delta H-{{E}_{a}}\] | |
| 555. |
Activation energy of a chemical reaction can be determined by |
| A. | evaluating rate constant at standard temperature |
| B. | evaluating velocities of reaction at two different temperatures |
| C. | evaluating rate constants at two different temperatures |
| D. | changing concentration of reactants |
| Answer» D. changing concentration of reactants | |
| 556. |
If half-life of a substance is 5 yrs, then the total amount of substance left after 15 years, when initial amount is 64 grams is |
| A. | 16g |
| B. | 2g |
| C. | 32g |
| D. | 8g |
| Answer» E. | |
| 557. |
The rate constant for a first order reaction whose half life is 480 sec, is: |
| A. | \[1.44\times {{10}^{-3}}se{{c}^{-1}}\] |
| B. | \[1.44\times se{{c}^{-1}}\] |
| C. | \[0.72\times {{10}^{-3}}se{{c}^{-1}}\] |
| D. | \[2.88\times {{10}^{-3}}se{{c}^{-1}}\] |
| Answer» B. \[1.44\times se{{c}^{-1}}\] | |
| 558. |
The hypothetical reaction \[{{A}_{2}}+{{B}_{2}}\xrightarrow{{}}2AB\]; follows the following mechanism \[{{A}_{2}}\xrightarrow{Fast}A+A,\] \[A+{{B}_{2}}\xrightarrow{slow}AB+B,A+B\xrightarrow{Fast}AB\] The order of the overall reaction is |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 44230 |
| Answer» E. | |
| 559. |
The rate equation for a reaction, \[{{N}_{2}}O\xrightarrow{{}}{{N}_{2}}+1/2{{O}_{2}}\] is Rate \[=k{{[{{N}_{2}}O]}^{0}}=k.\] If the initial concentration of the reactant is a mol\[Li{{t}^{-1}}\], the half-life period of the reaction is |
| A. | \[{{t}_{\frac{1}{2}}}=\frac{a}{2k}\] |
| B. | \[-{{t}_{\frac{1}{2}}}=ka\] |
| C. | \[{{t}_{\frac{1}{2}}}=\frac{a}{k}\] |
| D. | \[{{t}_{\frac{1}{2}}}=\frac{k}{a}\] |
| Answer» B. \[-{{t}_{\frac{1}{2}}}=ka\] | |
| 560. |
In a chemical reaction A is converted into B. The rates of reaction, starting with initial concentrations of A as \[2\times {{10}^{-3}}M\] and \[1\times {{10}^{-3}}M,\] are equal to \[2.40\times {{10}^{-4}}M{{s}^{-1}}\] and \[0.60\times {{10}^{-4}}M{{s}^{-1}}\] respectively. The order of reaction with respect to reactant A will be |
| A. | 0 |
| B. | 1.5 |
| C. | 1 |
| D. | 2 |
| Answer» E. | |
| 561. |
The rate constant of a reaction with a virus is \[3.3\times {{10}^{-4}}{{s}^{-1}}\]. Time required for the virus to become 75% inactivated is |
| A. | 35 min |
| B. | 70 min |
| C. | 105 min |
| D. | 17.5 min |
| Answer» C. 105 min | |
| 562. |
A Geigger Muller counter is used to study the radioactive process. In the absence of radioactive substance A, it counts 3 disintegration per second (dps). At the start in the presence of A, it records 23 dps; and after 10 min 13 dps, (i) What does it count after 20 min (ii) What is the half life of A? |
| A. | 8 dps, 10 min |
| B. | 5 dps, 10 min |
| C. | 5 dps, 20 min |
| D. | 5 dps, 5 min |
| Answer» B. 5 dps, 10 min | |
| 563. |
A radioactive isotope having a half - life period of 3 days was received after 12 days. If 3g of the isotope is left in the container, what would be the initial mass of the isotope? |
| A. | 12g |
| B. | 36g |
| C. | 48g |
| D. | 24g |
| Answer» D. 24g | |
| 564. |
For a first order reaction, a plot of log \[\left( a-x \right)\] against time is a straight line with a negative slope equal to |
| A. | \[\frac{-k}{2.303}\] |
| B. | \[-2.303k\] |
| C. | \[\frac{2.303}{k}\] |
| D. | \[-\frac{{{E}_{a}}}{2.303R}\] |
| Answer» B. \[-2.303k\] | |
| 565. |
The slope in Arrhenius plot, is equal to: |
| A. | \[-\frac{{{E}_{a}}}{2.303R}\] |
| B. | \[\frac{{{E}_{a}}}{R}\] |
| C. | \[-\frac{R}{2.303{{E}_{a}}}\] |
| D. | None of these |
| Answer» B. \[\frac{{{E}_{a}}}{R}\] | |
| 566. |
The activation energy for a simple chemical reaction \[A\to B\] is \[{{E}_{a}}\] in forward direction. The activation energy for reverse reaction |
| A. | is always double of \[{{E}_{a}}\] |
| B. | is negative of \[{{E}_{a}}\] |
| C. | is always less than \[{{E}_{a}}\] |
| D. | can be less than or more than \[{{E}_{a}}\] |
| Answer» E. | |
| 567. |
A chemical reaction was carried out at 300 K and 280 K. The rate constants were found to be \[{{k}_{1}}\] and \[{{k}_{2}}\] respectively, then |
| A. | \[{{k}_{2}}=4{{k}_{1}}\] |
| B. | \[{{k}_{2}}=2{{k}_{1}}\] |
| C. | \[{{k}_{2}}=0.25\,{{k}_{1}}\] |
| D. | \[{{k}_{2}}=0.5{{k}_{1}}\] |
| Answer» D. \[{{k}_{2}}=0.5{{k}_{1}}\] | |
| 568. |
When a biochemical reaction is carried out in laboratory in the absence of enzyme then rate of reaction obtained is \[{{10}^{-6}}\] times, then activation energy of reaction in the presence of enzyme is |
| A. | \[\frac{6}{RT}\] |
| B. | different from \[{{E}_{a}}\] obtained in laboratory, |
| C. | P is required |
| D. | can't say anything |
| Answer» C. P is required | |
| 569. |
For an exothermic reaction, the energy of activation of the reactants is |
| A. | equal to the energy of activation of products |
| B. | less than the energy of activation of products |
| C. | greater than the energy of activation of products |
| D. | sometimes greater and sometimes less than that of the products |
| Answer» C. greater than the energy of activation of products | |
| 570. |
A catalyst is a substance which: |
| A. | is always in the same phase as in the reaction |
| B. | alters the equilibrium in a reaction |
| C. | does not participate in the reaction but alters the rate of reaction |
| D. | participates in the reaction and provides an easier pathway for the same |
| Answer» D. participates in the reaction and provides an easier pathway for the same | |
| 571. |
A homogeneous catalytic reaction takes place through the three alternative plots A, B and C shown in the given figure. Which one of the following indicates the relative ease with which the reaction can take place? |
| A. | A>B>C |
| B. | C>B>A |
| C. | A>C>B |
| D. | A=B=C |
| Answer» C. A>C>B | |
| 572. |
The activation energies of the forward and backward reactions in the case of a chemical reaction are 30.5 and 45.4 kJ/mol respectively. The reaction is: |
| A. | exothermic |
| B. | endothermic |
| C. | neither exothermic nor endothermic |
| D. | independent of temperature |
| Answer» B. endothermic | |
| 573. |
In the presence of an acid, the initial concentration of cane sugar was reduced from 0.20 to 0.10 M in 5 hours and from 0.2 to 0.05 M in 10 hours. The reaction is of; |
| A. | Zero order |
| B. | First order |
| C. | Second order |
| D. | Third order |
| Answer» C. Second order | |
| 574. |
The order of a reaction, with respect to one of the reacting component Y, is zero. It implies that: |
| A. | the reaction is going on at a constant rate |
| B. | the rate of reaction does not vary with temperature |
| C. | the reaction rate is independent of the concentration of Y |
| D. | the rate of formation of the activated complex is zero |
| Answer» D. the rate of formation of the activated complex is zero | |
| 575. |
The half-life for the virus inactivation if in the beginning 1.5% of the virus is inactivated per minute is (Given: The reaction is of first order) |
| A. | 76 min |
| B. | 66 min |
| C. | 56 min |
| D. | 46 min |
| Answer» E. | |
| 576. |
In the reaction\[A\to B+C\], rate constant is\[0.001\text{ }M{{s}^{-1}}\]. If we start with 1 M of A then cone. of A and B after 10 minuter are respectively. |
| A. | 0.5 M, 0.5 M |
| B. | 0.6 M, 0.4 M |
| C. | 0.4 M, 0.6 M |
| D. | 0.6 M 0.5 M |
| Answer» D. 0.6 M 0.5 M | |
| 577. |
The reaction \[A\to B\] follows first order kinetics. The time taken for 0.8 mole of A to produce 0.6 mole of B is 1 hour. What is the time taken for conversion of 0.9 mole of A to produce 0.675 mole of B? |
| A. | 2 hours |
| B. | 1 hour |
| C. | 0.5 hour |
| D. | 0.25 hour |
| Answer» C. 0.5 hour | |
| 578. |
Consider the reaction: \[{{N}_{2}}(g)+3{{H}_{2}}(g)\to 2N{{H}_{3}}(g)\] The equality relationship between \[\frac{d[N{{H}_{3}}]}{dt}\] and \[-\frac{d[{{H}_{2}}]}{dt}\] is |
| A. | \[+\frac{d[N{{H}_{3}}]}{dt}=-\frac{2}{3}\frac{d[{{H}_{2}}]}{dt}\] |
| B. | \[+\frac{d[N{{H}_{3}}]}{dt}=-\frac{3}{2}\frac{d[{{H}_{2}}]}{dt}\] |
| C. | \[\frac{d[N{{H}_{3}}]}{dt}=-\frac{d[{{H}_{2}}]}{dt}\] |
| D. | \[\frac{d[N{{H}_{3}}]}{dt}=-\frac{1}{3}\frac{d[{{H}_{2}}]}{dt}\] |
| Answer» B. \[+\frac{d[N{{H}_{3}}]}{dt}=-\frac{3}{2}\frac{d[{{H}_{2}}]}{dt}\] | |
| 579. |
A reaction proceeds by first order, 75% of this reaction was completed in 32 min. The time required for 50% completion is |
| A. | 8 min |
| B. | 16 min |
| C. | 20 min |
| D. | 24 min |
| Answer» C. 20 min | |
| 580. |
The rate of a first order reaction is \[1.5\times {{10}^{-2}}mol\text{ }{{L}^{-1}}{{\min }^{-1}}\] at 0.5 M concentration of the reactant. The half-life of the reaction is |
| A. | 0.383 min |
| B. | 23.1 min |
| C. | 8.73 min |
| D. | 7.53 min |
| Answer» C. 8.73 min | |
| 581. |
The rate constant of a zero order reaction is\[2.0\times {{10}^{-2}}mol\,{{L}^{-1}}{{s}^{-1}}\]. If the concentration of the reactant after 25 seconds is 0.5 M. What is the initial concentration? |
| A. | 0.5 M |
| B. | 1.25 M |
| C. | 12.5 M |
| D. | \[1.0\,M\] |
| Answer» E. | |
| 582. |
The instantaneous rate of disappearance of \[MnO_{4}^{-}\] ion in the following reaction is\[4.56\times {{10}^{-3}}M{{s}^{-1}}2MnO_{4}^{-}+10{{I}^{-}}+16{{H}^{+}}\to \] \[2M{{n}^{2+}}+5{{I}_{2}}+8{{H}_{2}}O\]The rate of appearance \[{{I}_{2}}\] is: |
| A. | \[4.56\times {{10}^{-4}}M{{s}^{-1}}\] |
| B. | \[1.14\times {{10}^{-2}}M{{s}^{-1}}\] |
| C. | \[1.14\times {{10}^{-3}}M{{s}^{-1}}\] |
| D. | \[5.7\times {{10}^{-3}}M{{s}^{-1}}\] |
| Answer» C. \[1.14\times {{10}^{-3}}M{{s}^{-1}}\] | |
| 583. |
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. | \[\left( m+n \right)\] |
| B. | \[\left( n-m \right)\] |
| C. | \[{{2}^{\left( n+m \right)}}\] |
| D. | \[\frac{1}{{{2}^{\left( m+n \right)}}}\] |
| Answer» D. \[\frac{1}{{{2}^{\left( m+n \right)}}}\] | |
| 584. |
The time required for 10% completion of a first order reaction at 298 K is equal to that required for its 25% completion at 308 K, If the pre-exponential factor for the reaction is \[3.56\times {{10}^{9}}{{s}^{-1}}\] the rate constant at 318 K is: |
| A. | \[18.39\text{ }kcal\text{ }mo{{l}^{-1}}\] |
| B. | \[20\,kcal\,mo{{l}^{-1}}\] |
| C. | \[16\,kcal\,mo{{l}^{-1}}\] |
| D. | \[21.5\,kcal\,mo{{l}^{-1}}\] |
| Answer» B. \[20\,kcal\,mo{{l}^{-1}}\] | |
| 585. |
Consider the following statements: I. Increase in concentration of reactant increases the rate of a zero order reaction. II. Rate constant k is equal to collision frequency A if \[{{E}_{a}}=0.\] III. Rate constant k is equal to collision frequency A if \[{{E}_{a}}=\infty .\] IV. In k Vs T is a straight line. V. In k Vs 1/T is a straight line. Correct statements are |
| A. | I and IV |
| B. | II and V |
| C. | III and IV |
| D. | II and III |
| Answer» C. III and IV | |
| 586. |
The velocity of a reaction is doubled for every \[10{}^\circ C\] rise in temp. If the temp. is raised to \[50{}^\circ C\]from \[0{}^\circ C\] the reaction velocity increases by about |
| A. | 12 times |
| B. | 16 times |
| C. | 32 times |
| D. | 50 times |
| Answer» D. 50 times | |
| 587. |
A reaction rate constant is given by \[k=1.2\times {{10}^{14}}{{e}^{-25000/RT}}se{{c}^{-1}}\]. It means |
| A. | log k versus log T will give a straight line with a slope as \[-25000\] |
| B. | log k versus T will give a straight line with slope as 25000 |
| C. | log k versus 1/T will give a straight line with slope as \[-25000/R\] |
| D. | log k versus 1/T will give a straight line |
| Answer» D. log k versus 1/T will give a straight line | |
| 588. |
In Arrhenius plot, intercept is equal to |
| A. | \[\frac{-{{E}_{a}}}{R}\] |
| B. | \[\ell nA\] |
| C. | \[\ell n\,K\] |
| D. | \[lo{{g}_{10}}A\] |
| Answer» C. \[\ell n\,K\] | |
| 589. |
The reason for almost doubling the rate of reaction on increasing the temperature of the reaction system by \[10{}^\circ C\] is |
| A. | The value of threshold energy increases |
| B. | Collision frequency increases |
| C. | The fraction of the molecule having energy equal to threshold energy or more increases |
| D. | Activation energy decreases |
| Answer» C. The fraction of the molecule having energy equal to threshold energy or more increases | |
| 590. |
A catalyst lowers the activation energy of a certain reaction from 83.314 to \[75\text{ }kJ\text{ }mo{{l}^{-1}}\] at 500 K. What will be the rate of reaction as compared to uncatalysed reaction? Assume other things being equal. |
| A. | Double |
| B. | 28 times |
| C. | 7.38 times |
| D. | \[7.38\times {{10}^{3}}\]times |
| Answer» D. \[7.38\times {{10}^{3}}\]times | |
| 591. |
For a chemical reaction \[{{t}_{1/2}}\] is 2.5 hours at room temperature. How much of the reactant will be left after 7.5 hours if initial weight of reactant was 160g? |
| A. | 10 g |
| B. | 40 g |
| C. | 80 g |
| D. | 20 g |
| Answer» E. | |
| 592. |
For the first order reaction \[A\xrightarrow{{}}B+C\] is carried out at\[27{}^\circ C\]. If \[3.8\times {{10}^{-16}}\] % of the reactant molecules exists in the activated state, the \[{{E}_{4}}\](activation energy) of the reaction is: |
| A. | 12 kJ/mol |
| B. | 831.4 kJ/mol |
| C. | 100 kJ/mol |
| D. | 88.57 kJ/mol |
| Answer» D. 88.57 kJ/mol | |
| 593. |
A first order reaction is 50% completed in 20 minutes at \[27{}^\circ C\] and in 5 minutes at\[47{}^\circ C\]. The energy of activation of the reaction is: |
| A. | 43.85 kJ/mol |
| B. | 55.14 kJ/mol |
| C. | 11.97 kJ/mol |
| D. | 6.65 kJ/mol |
| Answer» C. 11.97 kJ/mol | |
| 594. |
The time taken for 90% of a first order reaction to complete is approximately |
| A. | 1.1 times that of half-life |
| B. | 2.2 times that of half-life |
| C. | 3.3 times that of half-life |
| D. | 4.4 times that of half-life |
| Answer» D. 4.4 times that of half-life | |
| 595. |
The rate constant of a reaction is\[0.0693\text{ }mi{{n}^{-1}}\]. Starting with 10 mol, the rate of the reaction after 10 minis |
| A. | \[0.0693\text{ }mol\text{ }mi{{n}^{-1}}\] |
| B. | \[0.0693\times 2\text{ }mol\text{ }mi{{n}^{-1}}\] |
| C. | \[0.0693\times 5\text{ }mol\text{ }mi{{n}^{-1}}\] |
| D. | \[0.0693\times {{\left( 5 \right)}^{2}}mol\text{ }mi{{n}^{-1}}\] |
| Answer» D. \[0.0693\times {{\left( 5 \right)}^{2}}mol\text{ }mi{{n}^{-1}}\] | |
| 596. |
A first order reaction is half-completed in 45 minutes. How long does it need for 99.9% of the reaction to be completed? |
| A. | 20 hours |
| B. | 10 hours |
| C. | \[7\frac{1}{2}\] hours |
| D. | 5 hours |
| Answer» D. 5 hours | |
| 597. |
The reaction \[L\xrightarrow{{}}M\] is started with 10.0 g of L. After 30 and 90 minutes 5.0 g and 1.25 g of L respectively are left. The order of the reaction is |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» C. 2 | |
| 598. |
For the reaction \[{{H}_{2}}\left( g \right)+B{{r}_{2}}\left( g \right)\to 2HBr\left( g \right),\] the experimental data suggest, rate\[=k[{{H}_{2}}]{{[B{{r}_{2}}]}^{1/2}}\]. The molecularity and order of the reaction are respectively |
| A. | \[2,\frac{3}{2}\] |
| B. | \[\frac{3}{2},\frac{3}{2}\] |
| C. | 1,1 |
| D. | \[1,\frac{1}{2}\] |
| Answer» B. \[\frac{3}{2},\frac{3}{2}\] | |
| 599. |
In the reaction,\[A+2B\xrightarrow{{}}6C+2D\], If the initial rate \[-\frac{d[A]}{dt}\] at t = 0 is \[2.6\times {{10}^{-2}}M\text{ }se{{c}^{-1}}\] what will be the value of \[\frac{d[B]}{dt}\] at\[t=0\]? |
| A. | \[8.5\times {{10}^{-2}}M\text{ }se{{c}^{-1}}\] |
| B. | \[2.5\times {{10}^{-2}}M\text{ }se{{c}^{-1}}\] |
| C. | \[5.2\times {{10}^{-2}}M\text{ }se{{c}^{-1}}\] |
| D. | \[7.5\times {{10}^{-2}}M\text{ }se{{c}^{-1}}\] |
| Answer» D. \[7.5\times {{10}^{-2}}M\text{ }se{{c}^{-1}}\] | |
| 600. |
Which of the following will react at the highest rate? |
| A. | 1 mole of A and 1 mole of B in a 1 -L vessel |
| B. | 2 mole of A and 2 mole of B in a 2-L vessel |
| C. | 3 mole of A and 3 mole of B in a 3-L vessel |
| D. | All would react at the same rate |
| Answer» E. | |