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Chemical Kinetics · Question 68

AIPMT 2003MCQEasy📈 Topic in 0% papers+4−1
1

The activation energy for a simple chemical reaction A B is Ea in forward direction. The activation energy for reverse reaction

  1. is negative of Ea
  2. is always less than Ea
  3. can be less than or more than Ea
  4. is always double of Ea

Answer

(3) can be less than or more than Ea

Solution

From the energy profile diagram, both forward and reverse reactions pass through the same activated complex.

⇒ Ea(b) = Ea(f) - H

∵ For an exothermic reaction ( H < 0): Ea(b) > Ea

∵ For an endothermic reaction ( H > 0): Ea(b) < Ea

∴ The activation energy for the reverse reaction can be less than or more than Ea, depending on the sign of H.

Answer: (3)

AIPMT 2003

Keep practising — Chemical Kinetics

2

The radioisotope, tritium (13H) has a half-life of 12.3 years. If the initial amount of tritium is 32 mg, how many milligrams of it would remain after 49.2 years?

  1. 1 mg
  2. 2 mg
  3. 4 mg
  4. 8 mg
AIPMT 2003
3

2A B + C It would be a zero order reaction when

  1. the rate of reaction is proportional to square of concentration of A
  2. the rate of reaction remains same at any concentration of A
  3. the rate remains unchanged at any concentration of B and C
  4. the rate of reaction doubles if concentration of B is increased to double
AIPMT 2002
4

When a bio-chemical reaction is carried out in laboratory, outside the human body in absence of enzyme, then rate of reaction obtained is 10-6 times, the activation energy of reaction in the presence of enzyme is

  1. 6/RT
  2. P is required
  3. different from Ea obtained in laboratory
  4. can't say anything.
AIPMT 2001
5

For the reaction; 2N2O5 4NO2 + O2 rate and rate constant are 1.02 10-4 and 3.4 10-5 s-1 respectively, then concentration of N2O5 at that time will be

  1. 1.732
  2. 3
  3. 1.02 10-4
  4. 3.4 105
AIPMT 2001
6

A human body required 0.01 m activity of radioactive substance after 24 hours. Half life of radioactive substance is 6 hours. Then injection of maximum activity of radioactive substance that can be injected is

  1. 0.08
  2. 0.04
  3. 0.16
  4. 0.32
AIPMT 2001
7

For the reaction 6H+ + BrO3- + 5Br- 3Br2 + 3H2O which of the following relation correctly represents the consumption and formation of products.

  1. d[Br2]dt = - 35 d[Br-]dt
  2. d[Br2]dt = 35 d[Br-]dt
  3. d[Br2]dt = - 53 d[Br-]dt
  4. d[Br2]dt = 53 d[Br-]dt
AIPMT 2000
8

A 300 g radioactive sample has a half-life of 3 hours. After 18 hours, the remaining quantity is

  1. 4.68 g
  2. 2.34 g
  3. 3.34 g
  4. 9.37 g
AIPMT 2000

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