Class 12 Exam  >  Class 12 Questions  >  Consider the following statements(i) First or... Start Learning for Free
Consider the following statements
(i) First order reaction completes in infinite time
(ii) Average life is independent of concentation for first order reactions
(iii) t75% = 1.5 t1/2 for zero order reaction
(iv) t75% = 2t1/2 for first order reaction
Correct among the following are
  • a)
    (i),(iii) and (iv)
  • b)
    (ii),(iv)
  • c)
    (i),(ii)
  • d)
    All are correct
Correct answer is option 'A'. Can you explain this answer?
Most Upvoted Answer
Consider the following statements(i) First order reaction completes in...
First order reaction completes in infinite time
A first order reaction follows the rate equation: rate = k[A], where [A] is the concentration of the reactant and k is the rate constant. The integrated rate equation for a first order reaction is: ln([A]t/[A]0) = -kt, where [A]t is the concentration of the reactant at time t, and [A]0 is the initial concentration of the reactant.

From the integrated rate equation, we can see that as t approaches infinity, ln([A]t/[A]0) approaches -∞. This means that the concentration of the reactant decreases indefinitely as time increases. Therefore, it can be concluded that a first order reaction completes in infinite time.

Average life is independent of concentration for first order reactions
The average life of a reactant molecule is the average time it takes for the reactant concentration to decrease to 1/e (approximately 37%) of its initial value. For a first order reaction, the average life can be calculated using the equation: average life = 1/(k[A]0).

From the equation, we can see that the average life is inversely proportional to the initial concentration [A]0. As [A]0 increases, the average life decreases, and vice versa. Therefore, the average life is dependent on the concentration for first order reactions, and statement (ii) is incorrect.

t75% = 1.5 t1/2 for zero order reaction
The half-life of a reaction is the time it takes for the reactant concentration to decrease to half of its initial value. For a zero order reaction, the integrated rate equation is: [A]t = [A]0 - kt.

From the integrated rate equation, we can see that when [A]t is 75% of [A]0, [A]t = [A]0 - k*t75% = [A]0 - 0.75[A]0 = 0.25[A]0. Solving for t75%, we get t75% = 0.25[A]0/k.

The half-life of a zero order reaction is given by t1/2 = [A]0/2k.

Substituting the values, we get t75% = 0.25[A]0/k = (0.5 t1/2)/2 = 0.5 t1/2/2 = 1.5 t1/2.

Therefore, statement (iii) is correct.

t75% = 2t1/2 for first order reaction
For a first order reaction, the integrated rate equation is: ln([A]t/[A]0) = -kt.

When [A]t is 75% of [A]0, [A]t = [A]0 - k*t75% = [A]0 - 0.75[A]0 = 0.25[A]0. Solving for t75%, we get t75% = 0.25[A]0/k.

The half-life of a first order reaction is given by t1/2 = ln(2)/k.

Substituting the values, we get t75% = 0.25[A]0/k = (ln(2)/
Community Answer
Consider the following statements(i) First order reaction completes in...
C
Explore Courses for Class 12 exam

Similar Class 12 Doubts

Read the passage given below and answer the following questions:The rate of a reaction, which may also be called its velocity or speed, can be defined with relation to the concentration of any of the reacting substances, or to that of any product of the reaction. If the species chosen is a reactant which has a concentration c at time t the rate is - dc/dt, while the rate with reference to a product having a concentration x at time t is dx/dt. Any concentration units may be used for expressing the rate; thus, if moles per liter are employed for concentration and seconds for the time, the units for the rate are moles litre–1sec–1. For gas reactions pressure units are sometimes used in place of concentrations, so that legitimate units for the rate would be (mm. Hg) sec–1 and atm. sec–1 The order of a reaction concerns the dependence of the rate upon the concentrations of reacting substances; thus, if the rate is found experimentally to be proportional to the ath power of the concentration of one of the reactants A, to the both power of the concentration of a second reactant B, and so forth, via., rate = k CAα CAβ the over-all order of the reaction is simply n = α + β + ----- (2) Such a reaction is said to be of the αth order with respect to the substance A, the βth order with respect to B.In the following questions, a statement of Assertion followed by a statement of Reason is given. Choose the correct answer out of the following choices on the basis of the above passage.Assertion: For a reaction: P + 2Q → Products, Rate = k [P]1/2[Q]1 so the order of reaction is 1.5Reason: Order of reaction is the sum of stoichiometric coefficients of the reactants.

Read the passage given below and answer the following questions:The rate of a reaction, which may also be called its velocity or speed, can be defined with relation to the concentration of any of the reacting substances, or to that of any product of the reaction. If the species chosen is a reactant which has a concentration c at time t the rate is - dc/dt, while the rate with reference to a product having a concentration x at time t is dx/dt. Any concentration units may be used for expressing the rate; thus, if moles per liter are employed for concentration and seconds for the time, the units for the rate are moles litre–1sec–1. For gas reactions pressure units are sometimes used in place of concentrations, so that legitimate units for the rate would be (mm. Hg) sec–1 and atm. sec–1 The order of a reaction concerns the dependence of the rate upon the concentrations of reacting substances; thus, if the rate is found experimentally to be proportional to the ath power of the concentration of one of the reactants A, to the both power of the concentration of a second reactant B, and so forth, via., rate = k CAα CAβ the over-all order of the reaction is simply n = α + β + ----- (2) Such a reaction is said to be of the αth order with respect to the substance A, the βth order with respect to B.In the following questions, a statement of Assertion followed by a statement of Reason is given. Choose the correct answer out of the following choices on the basis of the above passage.Assertion: Reactions can occur at different speeds.Reason: Rate of reaction is also called speed of reaction.

Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer?
Question Description
Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer?.
Solutions for Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for Class 12. Download more important topics, notes, lectures and mock test series for Class 12 Exam by signing up for free.
Here you can find the meaning of Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer?, a detailed solution for Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer? has been provided alongside types of Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice Consider the following statements(i) First order reaction completes in infinite time(ii) Average life is independent of concentation for first order reactions(iii) t75%= 1.5 t1/2 for zero order reaction(iv) t75%= 2t1/2 for first order reactionCorrect among the following area)(i),(iii) and (iv)b)(ii),(iv)c)(i),(ii)d)All are correctCorrect answer is option 'A'. Can you explain this answer? tests, examples and also practice Class 12 tests.
Explore Courses for Class 12 exam
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev