#### 12th Standard Chemistry Chemical Kinetics English Medium Free Online Test One Mark Questions 2020 - 2021

12th Standard

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Chemistry

Time : 00:20:00 Hrs
Total Marks : 20
20 x 1 = 20
1. For a first order reaction A ⟶ B the rate constant is x min−1. If the initial concentration of A is 0.01M , the concentration of A after one hour is given by the expression.

(a)

001. e−x

(b)

1 x 10-2(1-e-60x)

(c)

(1x10-2)e-60x

(d)

none of these

2. Among the following graphs showing variation of rate constant with temperature (T) for a reaction, the one that exhibits Arrhenius behavior over the entire temperature range is

(a)

(b)

(c)

(d)

both (b) and (c)

3. For a reaction Rate = kacetone[]32 then unit of rate constant and rate of reaction respectively is

(a)

(mol L-1 S-1),(mol1/2L1/2S-1)

(b)

(mol-1/2L1/2s-1),(mol L-1s-1)

(c)

(mol1/2L1/2s-1),(molL-1s-1)

(d)

(molLs-1),(mol1/2L1/2s)

4. Consider the following statements :
(i) increase in concentration of the reactant increases the rate of a zero order reaction.
(ii) rate constant k is equal to collision frequency A if Ea = 0
(iii) rate constant k is equal to collision frequency A if Ea =0
(iv) a plot of ln (k) vs T is a straight line.
(v) a plot of ln (k) vs $\left( \cfrac { 1 }{ T } \right)$ is a straight line with a positive slope.
Correct statements are

(a)

(ii) only

(b)

(ii) and (iv)

(c)

(ii) and (v)

(d)

(i), (ii) and (v)

5. What is the activation energy for a reaction if its rate doubles when the temperature is raised from 200K to 400K? (R = 8.314 JK-1mol-1)

(a)

234.65 kJ mol-1 K-1

(b)

434.65 kJ mol-1 K-1

(c)

434.65 J mol-1 K-1

(d)

334.65 J mol-1 K-1

6. Assertion: rate of reaction doubles when the concentration of the reactant is doubles if it is a first order reaction.
Reason: rate constant also doubles
Codes:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false
(d) Both assertion and reason are false.

(a)

Both assertion and reason are true and reason is the correct explanation of assertion.

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

Assertion is true but reason is false

(d)

Both assertion and reason are false.

7. For the reaction ${ N }_{ 2 }{ O }_{ 5 }\left( g \right) \longrightarrow { 2NO }_{ 2 }\left( g \right) +\cfrac { 1 }{ 2 } { O }_{ 2 }\left( g \right)$ value of rate of disappearance of N2O5is given as 6.5 x 10-2 molL-1s-1 The rate of formation of NO2 and O2 is given respectively as

(a)

(3.25x10-2 mol L-1S-1) and (1.3 x10-2 mol L-1s-1

(b)

(1.3x10-2 mol L-1s-1) and (3.25 x10-2 mol L-1s-1)

(c)

(1.3x10-1 mol L-1s-1) and (3.25 x10-2 mol L-1s-1)

(d)

None of these

8.  If 75% of a first order reaction was completed in 60 minutes , 50% of the same reaction under the same conditions would be completed in

(a)

20 minutes

(b)

30 minutes

(c)

35 minutes

(d)

75 minutes

9. The correct difference between first and second order reactions is that (NEET)

(a)

A first order reaction can be catalysed; a second order reaction cannot be catalysed.

(b)

The half life of a first order reaction does not depend on [A0]; the half life of a second order reaction does depend on [A0].

(c)

The rate of a first order reaction does not depend on reactant concentrations; the rate of a second order reaction does depend on reactant concentrations.

(d)

The rate of a first order reaction does depend on reactant concentrations; the rate of a second order reaction does not depend on reactant concentrations.

10. This reaction follows first order kinetics. The rate constant at particular temperature is 2.303X10-2 hour-1 The initial concentration of cyclopropane is 0.25 M. What will be the concentration of cyclopropane after 1806 minutes? (log 2 = 0.3010)

(a)

0.125 M

(b)

0.215 M

(c)

0.25 x 2.303 M

(d)

0.05 M

11. 2N2O5 ⟶ NO2 + O2$\frac { d\left[ { N }_{ 2 }{ O }_{ 5 } \right] }{ dt }$ = k1[N2O5], $\frac { d\left[ { NO }_{ 2 } \right] }{ dt }$k2[N2O5] and $\frac { d{ O }_{ 2 } }{ dt }$ = k 3[N2O5], the relation between k1, k2 and k3 is

(a)

2k1 = 4k2 = k3

(b)

k1 = k= k3

(c)

2k1 = k2 = 4k3

(d)

2k1 = k2 = k3

12. For a reaction, 2A + B ⟶ 3C, The rate of appearance of C at time 't' is 1.2 x 10-4 mol L-1s-1. Identify the rate of reaction.

(a)

4 x10-5mol L-1s-1

(b)

4.5 x 10-1mol L-1s-1

(c)

3.6 x 10-4 mol L-1s-1

(d)

None of these

13. In pseudo-order reactions

(a)

The actual order of reaction is different from that expected using rate law expression

(b)

The concentration of at least one reactant is taken in large excess.

(c)

The concentration of reactant taken in excess may be taken as constant

(d)

All of these

14. What would be the activation energy of a reaction when the temperature is increased from 27oC to 37oC?

(a)

534 kJ mol-1

(b)

53.4 kJ mol-1

(c)

5.34 kJ mol-1

(d)

None of these

15. Which order reaction obeys the expression ${ t }_{ \frac { 1 }{ 2 } }\alpha \frac { 1 }{ \left[ A \right] } ?$

(a)

First

(b)

Second

(c)

Third

(d)

Zero

16. The addition of a catalyst during a chemical reaction alters which of the following quantities?

(a)

Activation energy

(b)

Entropy

(c)

Internal energy

(d)

Enthalpy

17. The given reaction
2 FeCl3 + SnCl2 ⟶ 2FeCl2 + SnCl4 is an example of

(a)

I order

(b)

II order

(c)

III order

(d)

None of these

18. What will be the rate constant of a I order reaction if its half life is given to be 20 min?

(a)

13.86 min-1

(b)

28.86 min-1

(c)

3.47 x 10-2 min-1

(d)

None of these

19. During a chemical reaction, the concentration of reaction

(a)

increases

(b)

decreases

(c)

remains constant

(d)

first increases and then decreases

20. The term A in Arrhenius equation is called as

(a)

Probability factor

(b)

Activation energy

(c)

Collision factor

(d)

Frequency factor