The chemical reaction, 2O3 3O2 proceeds as follows;

O3 O2 + O .....(Fast)

O+O3  2O2 ....(Slow)

The rate law expression should be:

  • r = K[O3]2

  • r = K[O3]2[O2]-1

  • r = K[O3][O2]

  • unpredictable

The rate of reaction becomes 2 times for every 10°C rise in temperature. How the rate of reaction will increase when temperature is increased from 30°C to 80°C?

  • 16

  • 32

  • 64

  • 128

The rate constant (K) for the reaction 2A +B  Product was found to be 2.5x10-5 litre mol-1 sec-1 after 15 sec, 2.60 x10-5 litre mol-1sec-1 after 30 sec and 2.55 x10-5litre mol-1 sec-1 after 50 sec. The order of reaction is:

  • 2

  • 3

  • zero

  • 1

A reaction A2 + B2  2AB occurs by the following mechanism;

A2  A + A               .....(slow)

A + B2  AB + B       .....(fast)

A + B  AB               .....(fast)

Its order would be:

  • 3/2

  • 1

  • 0

  • 2

For a given reaction, presence of catalyst reduces the energy of activation by 2 kcal at 27°C. The rate of reaction will be increased by:

  • 20 times

  • 14 times

  • 28 times

  • 2 times

What fraction of a reactant showing first order remains after 40 minute if t1/2 is 20 minute?

  • 1/4

  • 1/2

  • 1/8

  • 1/6

Rate equation for a second order reaction is:

  • K = (2.303/t) log {a/(a-x)}

  • K = (1/t) log {a/(a-x)}

  • K = (1(a)t-1(ao)t)* 1t

  • K = (1/t2) log {a/(a-x)}

If 2M, 1L solution of acetic acid is added to 3M, 1L ethyl alcohol then the following elementary reaction takes place.

CH3COOH + C2H5OH  CH3COOC2H5 + H20

If each solution is diluted by 1 litre then the initial rate becomes how many times:-

  • 4

  • 2

  • 0.5

  • 0.25

For the reaction 2NO2 + F2 → 2NO2F, following

mechanism has been provided,

 NO2 + F2   slow  NO2F+F

NO2 + F   fast NO2F

Thus, rate expression of the above

reaction can be written as:

  • r = K[NO2]2[F2]

  • r = K[NO2 ][F2]

  • r = K[NO2]

  • r = K[F2]

For the reaction:

[Cu(NH3)4]2+ + H2O[Cu(NH3)3H2O]2+ + NH3

the net rate of reaction at any time is given by, net rate =

2.0x10-4 [Cu(NH3)4]2+[H2O] - 3.0x105 [Cu(NH3 )3 H20]2+[NH3]

Then correct statement is/are :

  • rate constant for forward reaction = 2 x 10-4

  • rate constant for backward reaction = 3 x 105

  • equilibrium constant for the reaction = 6.6 x 10-10

  • all of the above

Rate constant of reaction can be expressed by Arrhenius equation as,

                             K=Ae-EaRT   

In this equation, Ea represents:

  • the energy above which all the colliding molecules will react

  • the energy below which colliding molecules will not react

  • the total energy of the reacting molecules at a temperature, T

  • the fraction of molecules with energy greater than the activation energy of the reaction

Consider the chemical reaction,

N2g+3H2g2NH3g

The rate of this reaction can be expressed in terms of time derivative of concentration of  N2 g, H2g and NH3g.

The correct relationship amongest the rate expressions is: 

  • Rate =-dN2dt=-13 dH2dt=12 dNH3dt

  • Rate =-dN2dt=-3 dH2dt=2 dNH3dt

  • Rate =dN2dt=13 dH2dt=12 dNH3dt

  • Rate =-dN2dt=- dH2dt= dNH3dt

For a first order reaction A Product, the initial concentration of A is 0.1 M and after 40 minute it becomes 0.025 M. Calculate the rate of reaction at reactant concentration of 0.01M:

  • 3.47x10-4 M min-1

  • 3.47x10-5 M min-1

  • 1.735 x 10-6 M min-1

  • 1.735 x10-4 M min-1

Select the intermediate in the following reaction mechanism:

O3(g)  O2(g) +O(g)

O(g) +O3(g)  2O2(g)

  • O3(g)

  • O(g)

  • O2(g)

  • none of these

A reactant with initial concentration 1.386 mol litre-1 showing first order change takes 40 minute to become half. If it shows zero order change taking 20 minute to becomes half under the similar conditions, the ratio, K1/K0 for first order and zero order kinetics will be:

 

  • 0.5 mol-1 litre

  • 1.0 mol/litre

  • 1.5 mol/litre

  • 2.0 mol-1 litre

In a first order reaction, the concentration of the reactant is decreased from 1.0 M to 0.25M in 20 minute. The rate constant of the reaction would be:

  • 10min-1

  • 6.931 min-1

  • 0.6931 min-1

  • 0.06931 min-1

The following mechanism has been proposed for the reaction of NO with Br2 to form NOBr:

NO(g) + Br2(g)  NOBr2(g)

NOBr2(g) + NO(g) 2NOBr(g)

If the second step is the rate determining step, the order of the reaction with respect to NO(g) is:

  • 1

  • 0

  • 3

  • 2

For the reaction A           nB, at the point of intersection of two curves show, the [B] is can be given by:

  •  nA02

  •  A0n-1

  •  nA0n+1

  •  n-1n+1A0

The rate constant of a first order reaction is 4x10-3 sec-1. At a reactant concentration of 0.02 M, the rate of reaction would be:

  • 8 x 10-5 M sec-1

  • 4 x 10-3 M sec-1

  • 2 x 10-1 M sec-1

  • 4 x 10-1 M sec-1

If concentration of reactants is increased by 'X', the rate constant K becomes:

  • eK/X

  • K/X

  • K

  • X/K

In acidic medium the rate of reaction between (BrO3)- and Br- ions is given by the expression

-d(BrO3-)dt=KBrO3-Br-H+2

It means:

  • Rate constant of overall reaction is 4 sec-1

  • Rate of reaction is independant of the concentration of acid

  • The change in pH of the solution will not affect the rate

  • Doubling the conc. of H+ ions will increase the reaction rate by 4 times

A graph plotted between log (t) 50% vs. log (a) concentration is a straight line. What conclusion can you draw from the given graph?

  • n=1, t1/2 = 1/K.a

  • n=2, t1/2 = 1/a

  • n=1, t1/2 = 0.693/K

  • None of the above

For a first-order reaction A Products, the rate of reaction at [A] = 0.2 M is 1.0 x 10-2 mol litre-1 min-1. The half-life period for the reaction is-

  • 832 sec

  • 440 sec

  • 416 sec

  • 14 sec

The rate of a chemical reaction doubles for every 10°C rise of temperature. If the temperature is raised by 50°C, the rate of the reaction increases by about :

  • 10 times

  • 24 times

  • 32 times

  • 64 times

Consider the reaction:

Cl2(aq) + H2S(aq) → S(s) +2H+(aq) +2Cl-(aq)

The rate equation for this reaction is rate = k[Cl2][H2S] Which of these mechanisms is/are consistent with this rate equation?

A. Cl+ H2S → H+ Cl- +Cl+ + HS- (slow)

cl+ + HS- → H+ +Cl- + S (fast)

B. H2 H+ + HS- (fast equilibrium)

Cl2 + HS- → 2Cl- + H+ + S (slow)

  • A only

  • B only

  • Both A and B

  • Neither A nor B

3A  C + D, For this reaction it is observed that when initial concentration of A is 10 mole/lit then t1/2 value of this reaction is 40 min and when initial concentration of A is 20 mole / lit, t1/2 value has been changed into 20 min. Which of the following is true?

  •  The reaction is bimolecular reaction

  • This reaction is an example of radioactive disintegration

  •  The reaction is of 1st order

  • The order of the reaction is two

In the following reaction : xA →  yB

log-d[A]dt= log d[B]dt + 0.3 

where -ve sign indicates the rate of disappearance of the reactant. Then x : y is -

  • 1:2

  • 2:1

  • 3:1

  • 3:10


Half-life is independent of the concentration of reactant. After 10 minutes volume of N2 gas is 10L and after complete reaction, it is 50 L. Hence rate constant is :

  • 2.30310log 5 min-1

  • 2.30310 log 1.25 min-1

  • 2.30310 log 2 min-1

  • 2.30310 log 4 min-1

The activation energies of the forward and backward reactions in the case of a chemical reaction are 30.5 and 45.4 KJ/mol respectively. The reaction is

  • Exothermic

  • Endothermic

  • Neither exothermic nor endothermic

  • Independent of temperature

The t0.5 for the first order reaction.

PCl5(g) PCl3(g) + Cl2(g) is 20 min. The time in which the conc. of PClreduces to 25% of the initial conc. is close to 

  • 22 min

  • 40 min

  • 90 min

  • 50 min

0:0:1


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