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Chemical Kinetics · Question 17

JEE Main 2026 (Online) 24th January Morning ShiftMCQEasy📈 Topic in 6% papers+4−1
1

At 27 in presence of a catalyst, activation energy of a reaction is lowered by 10 kJ mol-1. The logarithm of ratio of k (catalysed)k (uncatalysed) is.... (Consider that the frequency factor for both the reactions is same)

  1. 1.741
  2. 0.1741
  3. 17.41
  4. 3.482

Answer

(1) 1.741

Solution

Arrhenius equation: k = A e-Ea/RT; A is the same for both reactions.

kcatkuncat = e(Ea - Ea')/RT

kcatkuncat = Ea - Ea'2.303RT

= 10 1032.303 8.314 300

= 100005744.1 = 1.741

Answer: (1)

JEE Main 2026 (Online) 24th January Morning Shift

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2

The half-life of 65Zn is 245 days. After x days, 75\% of original activity remained. The value of x in days is . (Nearest integer) (Given: 3 = 0.4771 and 2 = 0.3010)

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3

For the thermal decomposition of reactant AB(g), the following plot is constructed. [figure] The half-life of the reaction is 'x' min. x = min. (Nearest integer)

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4

[figure] Given above is the concentration vs time plot for a dissociation reaction : A nB. Based on the data of the initial phase of the reaction (initial 10 min), the value of n is .

  1. 2
  2. 5
  3. 4
  4. 3
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5

Observe the following reactions at T(K). I. A products. II. 5Br-(aq) + BrO3-(aq) + 6H+(aq) 3Br2(aq) + 3H2O(l) Both the reactions are started at 10.00 am. The rates of these reactions at 10.10 am are same. The value of - [Br-] t at 10.10 am is 2 10-4 mol L-1 min-1. The concentration of A at 10.10 am is 10-2 mol L-1. What is the first order rate constant (in min-1) of reaction I?

  1. 4 10-3
  2. 2 10-3
  3. 10-3
  4. 10-2
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6

A product (First order reaction). Three sets of experiments were performed for a reaction under similar experimental conditions: Run 1 100 mL of 10 M solution of reactant A Run 2 200 mL of 10 M solution of reactant A Run 3 100 mL of 10 M solution of reactant A + 100 mL of H2O added. The correct variation of rate of reaction is

  1. Run 1 = Run 2 = Run 3
  2. Run 3 < Run 1 < Run 2
  3. Run 1 < Run 2 < Run 3
  4. Run 3 < Run 1 = Run 2
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7

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8

Correct statements regarding Arrhenius equation among the following are : Choose the correct answer from the options given below :

  1. A and B Only
  2. B and D Only
  3. B and C Only
  4. A and C Only
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9

Consider A k1 B and C k2 D are two reactions. If the rate constant (k1) of the A B reaction can be expressed by the following equation 10 k = 14.34 - 1.5 104T/K and activation energy of C D reaction (Ea2) is 15th of the A B reaction (Ea1), then the value of (Ea2) is kJ mol-1. (Nearest Integer)

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10

Pre-exponential factors of two different reactions of same order are identical. Let activation energy of first reaction exceed the activation energy of second reaction by 20 kJ mol-1. If k1 and k2 are the rate constants of first and second reaction respectively at 300 K, then k2k1 will be . (nearest integer) [R = 8.3 J K-1 mol-1]

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11

Decomposition of A is a first order reaction at T(K) and is given by A(g) B(g) + C(g). In a closed 1 L vessel, 1 bar A(g) is allowed to decompose at T(K). After 100 minutes, the total pressure was 1.5 bar. What is the rate constant (in min-1) of the reaction? ( 2 = 0.3)

  1. 6.9 10-4
  2. 6.9 10-3
  3. 6.9 10-1
  4. 6.9 10-2
JEE Main 2026 (Online) 21st January Evening Shift

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