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Chemical Kinetics · Question 57

AIPMT 2007MCQMedium📈 Topic in 25% papers+4−1
1

If 60% of a first order reaction was completed in 60 minutes, 50% of the same reaction would be completed in approximately (log 4 = 0.60, log 5 = 0.70)

  1. 45 minutes
  2. 60 minutes
  3. 40 minutes
  4. 50 minutes

Answer

(1) 45 minutes

Solution

For a first order reaction, k = 2.303t [R]0[R]

60% completed ⇒ [R] = 40 when [R]0 = 100

k = 2.30360 10040

= 2.30360( 10 - 4) = 2.303 0.4060

For 50% completion, t1/2 = 2.303k 2, with 2 = 12 4 = 0.30

⇒ t1/2 = 2.303 0.30 602.303 0.40

= 45 minutes

Answer: (1)

AIPMT 2007

Keep practising — Chemical Kinetics

2

In a first-order reaction A B, if k is rate constant and initial concentration of the reactant A is 0.5 M, then the half-life is

  1. 2k
  2. 2k 0.5
  3. 2k
  4. 0.6930.5k
AIPMT 2007
3

The reaction of hydrogen and iodine monochloride is given as: H2(g) + 2ICl(g) 2HCl(g) + I2(g) This reaction is of first order with respect to H2(g) and ICl(g). The following mechanisms were proposed. Mechanism A: H2(g) + 2ICl(g) 2HCl(g) + I2(g) Mechanism B: H2(g) + ICl(g) HCl(g) + HI(g); slow HI(g) + ICl(g) HCl(g) + I2(g); fast Which of the above mechanism(s) can be consistent with the given information about the reaction?

  1. A and B both
  2. Neither A nor B
  3. A only
  4. B only
AIPMT 2007
4

Consider the reaction : N2(g) + 3H2(g) 2NH3(g) The equality relationship between d[NH3]dt and - d[H2]dt is

  1. d[NH3]dt = - d[H2]dt
  2. d[NH3]dt = - 13 d[H2]dt
  3. + d[NH3]dt = - 23 d[H2]dt
  4. + d[NH3]dt = - 32 d[H2]dt
AIPMT 2006
5

For the reaction, 2A + B 3C + D, which of the following does not express the reaction rate?

  1. - d[A]2dt
  2. - d[C]3dt
  3. - d[B]dt
  4. d[D]dt
AIPMT 2006
6

The rate of reaction between two reactants A and B decreases by a factor of 4 if the concentration of reactant B is doubled. The order of this reaction with respect to reactant B is

  1. 2
  2. -2
  3. 1
  4. -1
AIPMT 2005
7

For a first order reaction A B the reaction rate at reactant concentration of 0.01 M is found to be 2.0 10-5 mol L-1 s-1. The half-life period of the reaction is

  1. 30 s
  2. 220 s
  3. 300 s
  4. 347 s
AIPMT 2005
8

The rate of a first order reaction is 1.5 10-2 mol L-1 min-1 at 0.5 M concentration of the reactant. The half-life of the reaction is

  1. 0.383 min
  2. 23.1 min
  3. 8.73 min
  4. 7.53 min
AIPMT 2004
9

The temperature dependence of rate constant (k) of a chemical reaction is written in terms of Arrhenius equation, k = A e-E*/RT. Activation energy (E*) of the reaction can be calculated by plotting

  1. k vs T
  2. k vs 1 T
  3. log k vs 1T
  4. log k vs 1 T
AIPMT 2003
10

If the rate of the reaction is equal to the rate constant, the order of the reaction is

  1. 0
  2. 1
  3. 2
  4. 3
AIPMT 2003
11

The reaction A B follows first order kinetics. The time taken for 0.8 mole of A to produce 0.6 mole of B is 1 hour. What is the time taken for conversion of 0.9 mole of A to produce 0.675 mole of B?

  1. 1 hour
  2. 0.5 hour
  3. 0.25 hour
  4. 2 hours
AIPMT 2003

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