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Chemical Kinetics · Question 16

NEET (UG) 2022MCQMedium📈 Topic in 38% papers+4−1
1

The given graph is a representation of kinetics of a reaction [figure] The y and x axes for zero and first order reactions, respectively are

  1. zero order (y = concentration and x = time), first order (y = t1/2 and x = concentration)
  2. zero order (y = concentration and x = time), first order (y = rate constant and x = concentration)
  3. zero order (y = rate and x = concentration), first order (y = t1/2 and x = concentration)
  4. zero order (y = rate and x = concentration), first order (y = rate and x = t1/2)

Answer

(3) zero order (y = rate and x = concentration), first order (y = t1/2 and x = concentration)

Solution

The graph is a straight line parallel to the x-axis, i.e., y does not depend on x.

Zero order: Rate = k[R]0 = k

⇒ rate is independent of concentration, so a plot of rate (y) vs concentration (x) is a horizontal line. (A plot of [R] vs t is a straight line with negative slope, not horizontal.)

First order: t1/2 = 0.693k

⇒ as per NCERT, half-life of a first order reaction is independent of the initial concentration, so t1/2 (y) vs concentration (x) is a horizontal line.

∴ Zero order: y = rate, x = concentration; first order: y = t1/2, x = concentration.

Answer: (3)

NEET (UG) 2022

Keep practising — Chemical Kinetics

2

For 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

  1. 1.3818
  2. 0.9212
  3. 0.4606
  4. 0.2303
NEET (UG) 2022
3

The half life of a first order reaction is 2000 years. If the concentration after 8000 years is 0.02 M, then the initial concentration was :

  1. 0.04 M
  2. 0.16 M
  3. 0.32 M
  4. 0.08 M
NEET (UG) 2022 (Phase 2)
4

For a chemical reaction 4A + 3B 6C + 9D Rate of formation of C is 6 10-2 mol L-1 s-1 and rate of disappearance of A is 4 10-2 mol L-1 s-1. The rate of reaction and amount of B consumed in interval of 10 seconds, respectively will be :

  1. 10 10-2 mol L-1 s-1 and 30 10-2 mol L-1
  2. 1 10-2 mol L-1 s-1 and 30 10-2 mol L-1
  3. 10 10-2 mol L-1 s-1 and 10 10-2 mol L-1
  4. 1 10-2 mol L-1 s-1 and 10 10-2 mol L-1
NEET (UG) 2022 (Phase 2)
5

For a reaction, A B, enthalpy of reaction is -4.2 kJ mol-1 and enthalpy of activation is 9.6 kJ mol-1. The correct potential energy profile for the reaction is shown in option.

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET (UG) 2021
6

The slope of Arrhenius plot ( ln k v/s 1T ) of first order reaction is -5 103 K. The value of Ea of the reaction is. Choose the correct option for your answer. [Given R = 8.314 J K-1 mol-1]

  1. -83 kJ mol-1
  2. 41.5 kJ mol-1
  3. 83.0 kJ mol-1
  4. 166 kJ mol-1
NEET (UG) 2021
7

An increase in the concentration of the reactants of a reaction leads to change in :

  1. heat of reaction
  2. threshold energy
  3. collision frequency
  4. activation energy
NEET (UG) 2020
8

The 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 :

  1. 200 s
  2. 500 s
  3. 1000 s
  4. 100 s
NEET (UG) 2020
9

If 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 :

  1. t = 4.606k
  2. t = 2.303k
  3. t = 0.693k
  4. t = 6.909k
NEET (UG) 2019
10

For the chemical reaction N2(g) + 3H2(g) 2NH3(g) the correct option is :

  1. - d[N2]dt = 2 d[NH3]dt
  2. - d[N2]dt = 12 d[NH3]dt
  3. 3 d[H2]dt = 2 d[NH3]dt
  4. - 13 d[H2]dt = - 12 d[NH3]dt
NEET (UG) 2019
11

The correct difference between first and second order reactions is that

  1. 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
  2. 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
  3. a first-order reaction can be catalysed; a second-order reaction cannot be catalysed
  4. 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
NEET 2018

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