NEET 2018 · ChemistryIntegrated ratePrevious Year Question

Which one of the following statements correctly describes the difference between a first-order and a second-order reaction?

Answer: (B) The half-life of a first-order reaction does not depend on $[A]_{0}$ ; the half-life of a second-order reaction does depend on $[A]_{0}$ . \textbf{Answer:} (B) The half-life of a first-order reaction does not depend on $[A]_{0}$ ; that of a second-order reaction does \textbf{Solution:} For a first-order reaction: $t_{1/2} = \frac{0.693}{k}$ which is independent of the initial concentration $[A]_{0}$ .

A.A first-order reaction can be catalysed; a second-order reaction cannot be catalysed
B.The half-life of a first-order reaction does not depend on $[A]_{0}$ ; the half-life of a second-order reaction does depend on $[A]_{0}$ ✓
C.The rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction does depend on reactant concentrations
D.The rate of a first-order reaction does depend on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations

Correct Answer

(B) The half-life of a first-order reaction does not depend on $[A]_{0}$ ; the half-life of a second-order reaction does depend on $[A]_{0}$

Solution & Explanation

\textbf{Answer:} (B) The half-life of a first-order reaction does not depend on $[A]_{0}$ ; that of a second-order reaction does \textbf{Solution:} For a first-order reaction: $t_{1/2} = \frac{0.693}{k}$ which is independent of the initial concentration $[A]_{0}$ . For a second-order reaction: $t_{1/2} = \frac{1}{k [ A ] _{0}}$ which depends on $[A]_{0}$ . Option (C) is false because the rate of a first-order reaction does depend on concentration, $rate = k [A]$ .

🎯

43,000+ questions in हिंदी & English · one-tap toggle

Practice NEET 2018 Chemistry — free, with instant solutions

43,000+ NEET questions solved step-by-step, chapter-wise, in the MedicNEET app.

Open →📚Practice all NEET Chemistry PYQs chapter-wise →💡Don't get it? Learn the Chemical Kinetics concepts →

← Chemistry Q45 Chemistry Q47 →

More NEET PYQ solutions

ChemIf the rate constant of a reaction is 0.03 s-1, how much time does it take for 7.2 mol L-1 concentration of the reactant to get reduced to 0.9 mol L-1? (Given: 2 = 0.301)ChemIf the half-life t1/2 for a first order reaction is 1 minute, then the time required for 99.9% completion of the reaction is closest to ChemFor a certain reaction R -> Product, the plot of concentration [R] versus time is a straight line with a constant negative slope, as shown in the graph. The order of the reaction is:ChemThe given graph (drawn at constant temperature T) is a representation of the kinetics of a reaction. The plot of y versus x is a horizontal straight line parallel to the x-axis, i.e. y is constant and independent of x. The y and x axes for zero order and first order reactions, respectively, are:ChemFor a first order reaction A -> Products, initial concentration of A is 0.1 M, which becomes 0.001 M after 5 minutes. Rate constant for the reaction in min-1 is:ChemThe rate constant for a first order reaction is 4.606 10-3 s-1. The time required to reduce 2.0 g of the reactant to 0.2 g is:ChemA first order reaction has a rate constant of 2.303 10-3 s-1. The time required for 40 g of this reactant to reduce to 10 g will be (Given 10 2 = 0.3010):ChemIf the rate constant for a first order reaction is k, the time t required for the completion of 99% of the reaction is given by:

More: All NEET 2018 Chemistry PYQs · NEET Chemistry PYQs · All NEET PYQs · Previous year papers