Chemistry XII+ - Chemical Kinetics 02

Question : 1

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Hydrolysis of ester in alkaline medium is a

Options:

	Zero order reaction
	1st order reaction
	2nd order reaction
	3rd order reaction

Solution :

(3)

In alkaline medium,
Rate = k [Ester][NaOH]
∴ Second order

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Question : 2

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For the reaction aA + bB → product. If [B] is constant, rate doubles when concentration of A is quadrupled. If [A] is constant, rate triples when [B] is tripled. Then order of the above reaction is

Options:

	1
	3

Solution :

(3)

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Question : 3

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For the elementary reaction
A + 3B → product
If volume is made tripled, the rate becomes

Options:

	81 times
	27 times
	Unaffected

Solution :

(2)

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Question : 4

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Units of rate constant for decomposition of ammonia on hot platinum surface at high pressure

Options:

	mol L–1s–1
	s–1
	mol–1Ls–1
	mol–2L2s–1

Solution :

(1)

It’s a zero order reaction
k = mol L^–1s^–1

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Question : 5

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For a zero order reaction, the slope of the graph plotted between final concentration and time is where k = rate constant, [A₀] = initial concentration

Options:

	k
	–k
	[A0]
	–[A0]

Solution :

(2)

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Question : 6

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If rate constant for a zero order reaction is 2 × 10^–2 mol L^–1 min^–1, then in how much time initial concentration is reduced to 40%?

Options:

	3000 hrs
	50 hrs
	33.3 hrs
	3.33 hrs

Solution :

(2)

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Question : 7

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Which is incorrect regarding molecularity of a reaction?

Options:

	It is the number of reacting species which must collide simultaneously in order to bring about chemical reaction
	Molecularity cannot be zero or a non-integer
	Molecularity is applicable for elementary as well as complex reactions
	All of these

Solution :

(3)

Molecularity is applicable only for elementary reaction

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Question : 8

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If for the reaction 2A + B₂ → 2AB₂. Order w.r.t. A is 2 and that w.r.t. B₂ is 1. Then in the following table values of X and Y are respectively

    Expt Initial [A]                Initial [B₂]                     Rate
     (mol L^–1)                        (mol L^–1)                    (mol L^–1 s^–1)

I    0.20                                   0.20                              

II                                      0.20                         0.384

III   0.20                                 0.40                         0.192

Options:

	0.096, 0.20
	0.096, 0.40
	0.192, 0.40
	0.192, 0.20

Solution :

 (2)

Comparing I & III,
= 0.096
Comparing I & II
= 0.40

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Question : 9

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If after every 5 min, the rate of the reaction remains same, then order of reaction is

Options:

	Zero
	Ist
	IInd
	IIIrd

Solution :

(1)

As the rate remains same, hence it is zero order reaction

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Question : 10

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For the reaction 2HI Au
Surface  H₂ + I₂
The order and molecularity of above reaction are respectively

Options:

	0, 2
	0, 0
	2,2
	2, 0

Solution :

(1)

Order-zero Molecularity-two