Processing math: 21%

CBSE Questions for Class 12 Engineering Chemistry Chemical Kinetics Quiz 5 - MCQExams.com

Here is another look at the reaction of crystal violet with sodium hydroxide, a first-order reaction (ln A v time).
What is the significance of the slope?
537147.jpg
  • The slope represents the change in concentration over time.
  • The slope represents the inverse of change in concentration over time.
  • The slope represents the negative value of the rate constant.
  • The slope represents the negative rate of product concentration over time.
A graph of concentration versus time data for a first-order reaction gives a straight line in which of the following plots of the data?
  • [A]t=kt+[A]0
  • ln[A]t=kt+ln[A]0
  • 1[A]t=kt+1[A]0
  • All of the above
  • None of the above
In a reaction mechanism consisting of elementary reaction steps where the relative rate of each is given, which of the following is most likely to be the rate-determining step?
  • A step labeled fast
  • A step labeled moderate
  • A step labeled slow
  • It is not possible to tell which step is rate determining from this information.
Reacting Cl with NO2Cl molecules produces NO2 and Cl2 gases.
Which of the following will require the lowest activation energy based on proper orientation for this reaction?
An experiment was performed to study the kinetics of the decomposition of substance X. The concentration of X, [X], was monitored over time as the reaction proceeded. The data are shown in the table above. The time interval between concentration measurements was 1.0 minutes(60s).
Time (s)[X]ln[X]1[X]
020.03.000.050
6010.02.300.100
1206.671.900.150
1805.001.610.200
2404.001.390.250
Which of the following best describes the reaction?
  • The decomposition of substance X is a zero-order reaction.
  • The decomposition of substance X is a first-order reaction.
  • The decomposition of substance X is a second-order reaction.
  • The decomposition of substance X is a third-order reaction.
In a given reaction under standard conditions in a closed container, which type of reaction would show no real increase in the rate of the reaction when the concentration of each reactant is doubled?
  • A zero order
  • A first order
  • A second order
  • A third order
A first order reaction is 60% complete in 20 minutes. How long will the reaction take to be 84% complete?
  • 54 mins
  • 68 mins
  • 40 mins
  • 76 mins
A plot of 1T vs. logk for a reaction gives the slope (1×104 K). The energy of activation for the reaction is :
(Given R=8.314 JK1mol1)
  • 1.202 kJmol1
  • 83.14 kJmol1
  • 8314 Jmol1
  • 191.47 kJmol1
The correct statement regarding the following energy diagrams is
574099_0e97e890a2f646b7beb83e8cd4a626ab.png
  • Reaction M is faster and less exothermic than Reaction N
  • Reaction M is slower and less exothermic than Reaction N
  • Reaction M is faster and more exothermic than Reaction N
  • Reaction M is slower and more exothermic than Reaction N
The activation energy of a chemical reaction can be determined by :
  • evaluating rate constants at two different temperatures
  • changing the concentration of reactants
  • evaluating the concentration of reactants at two different temperatures
  • evaluating rate constant at standard temperature
A given sample of milk turns sour at room temperature (27oC) in 5 hours. In a refrigerator at 3oC, it can be stored 10 times longer. The energy of activation for the souring of milk is :
  • 2.303×10R  kJmol1
  • 2.303×5R  kJmol1
  • 2.303×3R  kJmol1
  • 2.303×2.7R  kJmol1
When the concentration of a reactant of first order reaction is doubled, the rate becomes ________ times, but for ___________ order reaction, the rate remains same.
  • Four; zero
  • Two; zero
  • Zero; four
  • Zero; three
The unit of zero order rate constant is:
  • litre mol^{-1} sec^{-1}
  • mol litre^{-1} sec^{-1}
  • sec^{-1}
  • litre^{2} sec^{-1}
The excess energy which a molecule must posses to become active is known as:
  • kinetic energy
  • threshold energy
  • potential energy
  • activation energy
The unit of rate constant for zero order reaction is:
  • s^{-1}
  • mol\, L^{-1}s^{-1}
  • L\, mol^{-1}s^{-1}
  • L^2mol^{-2}s^{-1}
Which graph shows zero activation energy for reaction?
For a zero-order reaction with a rate constant k, the slope of the plot of reactant concentration against time is:
  • \dfrac{ k} {2.303}
  • k
  • -\dfrac {k}{2.303}
  • -k
The relationship between rate constant and half-life period of zero-order reaction is given by:
  • { t }_{ \frac { 1 }{ 2 } }={ \left[ A \right] }_{ 0 }2k
  • { t }_{ \frac { 1 }{ 2 } }=\dfrac { 0.693 }{ k }
  • { t }_{ \frac { 1 }{ 2 } }=\dfrac { { \left[ A \right] }_{ 0 } }{ 2k }
  • { t }_{ \frac { 1 }{ 2 } }=\dfrac { 2{ \left[ A \right] }_{ 0 } }{ k }
The half-life of ^{14}C is 5570 yr. How many years will it take 90% of a sample to decompose?
  • 5,570 yr
  • 17,700 yr
  • 18,510 yr
  • 50,100 yr
Collision theory is applicable to 
  • First order reactions
  • Zero order reactions
  • Bimolecular reactions
  • Intramolecular reactions
3A\longrightarrow B+C

It would be a zero-order reaction when:
  • The rate of reaction is proportional to square of concentration of A
  • The rate of reaction remains the same at any concentration of A
  • The rate remains unchanged at any concentration of B and C
  • The rate of reaction doubles if concentration of B is increased to double
A certain radioactive isotope decay has \alpha-emission,
_{ { Z }_{ 1 } }^{ { A }_{ 1 } }{ X }\longrightarrow _{ { Z }_{ 1 }-2 }^{ { A }_{ 1 }-4 }{ Y }
half life of X is 10 days. If 1 mol of X is taken initially in a sealed container, then what volume of helium will be collected at STP after 20 days?
  • 22.4 L
  • 11.2 L
  • 16.8 L
  • 33.6 L
One gram of ^{ 226 }{ Ra } has an activity of nearly 1 Ci. The half life of ^{ 226 }{ Ra } is
  • 1582 yrs
  • 12.5 hrs
  • 140 days
  • 4.5\times { 10 }^{ 9 } yrs
The order of reaction for which half-life period is independent of initial concentration is:
  • zero
  • first
  • second
  • third
A freshly prepared radio medicine has half life 2 hours. Its activity is 64 times the permissible safe value. The minimum time after which it would be possible to treat the patients with the medicine is:
  • 3 hrs
  • 9 hrs
  • 24 hrs
  • 12 hrs
For an endothermic reaction, where \Delta H represents the enthalpy of reaction, the minimum value for the energy of activation will be:
  • less than \Delta H
  • zero
  • equal to \Delta H
  • more than \Delta H
A first-order reaction has a half-life of 14.5\ hrs. What percentage of the reactant will remain after 24\ hrs?
  • 18.3%
  • 31.8%
  • 45.5%
  • 68.2%
The rates of a certain reaction at different time intervals are as follows:
\begin{matrix} Time(second) & 0 & 10 & 20 \\ Rate(mol\ L^{-1}s^{-1}) & 1.8\times { 10 }^{ -2 } & 1.82\times { 10 }^{ -2 } & 1.79\times { 10 }^{ -2 } \end{matrix}
The reaction is of:
  • zero order
  • first order
  • second order
  • third order
Which one of the following is not a first order reaction?
  • C{ H }_{ 3 }COOC{ H }_{ 3 }+{ H }_{ 2 }O\xrightarrow [ ]{ \quad { H }^{ + }\quad } C{ H }_{ 3 }COOH+C{ H }_{ 3 }OH
  • C{ H }_{ 3 }COO{ C }_{ 2 }{ H }_{ 5 }+NaOH\longrightarrow C{ H }_{ 3 }COONa+{ C }_{ 2 }{ H }_{ 5 }OH
  • 2{ H }_{ 2 }{ O }_{ 2 }\longrightarrow 2{ H }_{ 2 }O+{ O }_{ 2 }
  • 2{ N }_{ 2 }{ O }_{ 5 }\longrightarrow 4N{ O }_{ 2 }+{ O }_{ 2 }
Reaction, A+B\longrightarrow C+D+38kcal has activation energy 20kcal. Activation energy for the reaction, C+D\longrightarrow A+B\quad is:
  • 20kcal
  • -20kcal
  • 18kcal
  • 58kcal
At 500 K, the half-life period of a gaseous reaction at an initial pressure of 80 kPa is 350 sec. When the pressure is 40 kPa, the half life period is 175 sec; the order of the reaction is:
  • Zero
  • One
  • Two
  • Three
Which of the following is a first order reaction?
  • 2HI\longrightarrow { H }_{ 2 }+{ I }_{ 2 }
  • 2N{ O }_{ 2 }\longrightarrow 2NO+{ O }_{ 2 }
  • 2NO+{ O }_{ 2 }\longrightarrow 2N{ O }_{ 2 }
  • N{ H }_{ 4 }N{ O }_{ 2 }\longrightarrow { N }_{ 2 }+2{ H }_{ 2 }O
A substance reacts with initial concentration of a mol { dm }^{ -3 } according to zero order kinetics. The time it takes for the completion of the reaction is: (k= rate constant)
  • \dfrac { k }{ a }
  • \dfrac { a }{ 2k }
  • \dfrac { a }{ k }
  • \dfrac { 2k }{ a }
The decomposition of HI on the surface of gold is:
  • pseudo first order
  • zero order
  • first order
  • second order
For a zero order reaction which of the following relation is correct, where t_{1/2}\ and\ a are half-life and initial concentration respectively.
  • { t }_{ { 1 }/{ 2 } }\propto a
  • { t }_{ { 1 }/{ 2 } }\propto \dfrac { 1 }{ a }
  • { t }_{ { 1 }/{ 2 } }\propto { a }^{ 2 }
  • { t }_{ { 1 }/{ 2 } }\propto \dfrac { 1 }{ { a }^{ 2 } }
A drop of solution (volume 0.05 mL) contains 3\times { 10 }^{ -6 } mole of { H }^{ + }. If the rate constant of disappearance of { H }^{ + } is { 10 }^{ 7 } mol { litre }^{ -1 } { sec }^{ -1 }, how long would it take for { H }^{ + } in the drop to disappear?
  • 6\times { 10 }^{ -8 }\ sec
  • 6\times { 10 }^{ -9 }\ sec
  • 6\times { 10 }^{ -10 }\ sec
  • 6\times { 10 }^{ -12 }\ sec
The specific rate constant of a first order reaction depends on:
  • concentration of the reactants
  • concentration of the products
  • time
  • temperature
The rate constant of a reaction is found to be 3\times { 10 }^{ -3 } mol { L }^{ -1 } { min }^{ -1 }. The order of the reaction is:
  • 0
  • 1
  • 2
  • 1.5
The hydrolysis of ethyl acetate is a reaction of:
C{ H }_{ 3 }COO{ C }_{ 2 }{ H }_{ 5 }+{ H }_{ 2 }O\xrightarrow [  ]{ \quad { H }^{ + }\quad  } C{ H }_{ 3 }COOH+{ C }_{ 2 }{ H }_{ 5 }OH
  • zero order
  • first order
  • second order
  • third order
Graph between the concentration of the product 'x' and time 't' for A\rightarrow B is given above.
The graph between -\dfrac { d\left[ A \right]  }{ dt } and time 't' will be of the type:
661676_f86ebdaf4de04d2094016199e6fb6cb2.png
For a zero order reaction, A\longrightarrow P{ t }_{ { 1 }/{ 2 } } is: 
(k is the rate constant, [A]_0 is the initial concentration of A)
  • \dfrac { { \left[ A \right] }_{ 0 } }{ 2k }
  • \dfrac { \ln { 2 } }{ k }
  • \dfrac { 1 }{ k{ \left[ A \right] }_{ 0 } }
  • \dfrac { \ln { 2 } }{ { \left[ A \right] }_{ 0 }k }
Following is the graph between \log{{ t }_{ { 1 }/{ 2 } }} and \log { a } (a= initial concentration) for a given reaction at { 27 }^{ o }C. Hence, order of the reaction is:
661674_e8e498a2a5d14537967fbe6899017dc7.png
  • 0
  • 1
  • 2
  • 3
When the initial concentration of the reaction is doubled, the half-life is also doubled. The order of the reaction will be:
  • 0
  • 1
  • 2
  • 3
A substance having rate constant k and initial concentration a reacts according to zero order kinetics. What will be the time for the reaction to go to completion?
  • \dfrac { a }{ k }
  • \dfrac { k }{ a }
  • \dfrac { a }{ 2k }
  • \dfrac { 2k }{ a }
The time for half-life period of a certain reaction, A\rightarrow Product, is 1 hour, when the initial concentration of the reactant 'A' is 2 mol { L }^{ -1 }. How much time does it take for its concentration to come from 0.50 to 0.25 mol { L }^{ -1 } if it is a zero order reaction?
  • 0.25\ hr
  • 1\ hr
  • 4\ hrs
  • 0.5\ hr
Raw milk sours in about 4 h at 27^ o C, but in about 48 h in a refrigerator at 17^ o C. What is the activation energy for souring of milk ?
  • 78.3 kJ mol^{-1}
  • 46.21 kJ mol^{-1}
  • 23.5 kJ mol^{-1}
  • 80.8 kJ mol^{-1}
Which of the following is not correct for zero order reaction?
In the reaction, A+B\longrightarrow C+D, the rate \left( \dfrac { dx }{ dt }  \right) when plotted against time 't' gives a straight line parallel to time axis and at some time 't', \dfrac{dx}{dt}=k. The order and rate of reaction will be:
  • 1, k+1
  • 0, k
  • \left( 1+k \right) , 1
  • k, k+1
N_2+3H_2\rightleftharpoons 2NH_3 +22kcal
The activation energy for the forward reaction is 50kcal. What is the activation energy for the backward reaction?
  • -72 kcal
  • -28 kcal
  • +28 kcal
  • +72 kcal
For the first order reaction, t_{99}% = x \times t_{90}%, the value of x will be: 
  • 10
  • 6
  • 3
  • 2
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 12 Engineering Chemistry Quiz Questions and Answers