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Question Bank No: 1

1. If [A] is the concentration of A at any t and [A $]^{0}$ is its initial concentration, then for a zero order reaction,A $\to$ Products, the rate equation may be written as

a)		[A $]_{0}$ - [A]=k
b)		[A]- [A $]_{0}$ =k
c)		[A $]_{0}$ - [A]=kt
d)		[A $]_{0}$ = k[A]

2. A graph of In k $υ s (\frac{1}{T})$ has slope equal to

a)		- $\frac{E}{2.303 R}$
b)		+ $\frac{E_{a}}{R}$
c)		- $\frac{E_{a}}{2.303 R}$
d)		- $\frac{E_{a}}{R}$

3. While studying the decomposition of gaseous $N_{2} O_{5}$ it is observed that a plot of logarithm of its partial pressure versus time is linear.What is the order od the reaction?

a)		1
b)		1/2
c)		2
d)		0

4. Plotting a graph of log $t_{1 / 2}$ against log [A $]_{0}$ of a reactants for a first order reaction,the slope will be

a)		-1
b)		-2
c)		0
d)		+1

5. For a zero order reaction, A $\to$ B, a graph of rate $υ s$ time has slope equal to

a)		k
b)		-k
c)		zero
d)		-2.303k

6. The rate of reaction; 2A + B $\to$ Products, is given by the equation rate = k ${[A]}^{2} [B] .$ If B is present in excess,the order of the reaction would be

a)		3
b)		1
c)		2
d)		0

7. 75% of a first order reaction was completed in 32 minutes.The half-life of the reaction is

a)		24 min
b)		16 min
c)		32 min
d)		8 min

8. In a first order reaction,75% of the reactants disappeared in 1.386 hr.What is the rate constant?

a)		3.6 $\times 10^{- 3} S^{- 1}$
b)		1.389 $\times 10^{- 4} S^{- 1}$
c)		72 $\times 10^{- 3} S^{- 1}$
d)		1.8 $\times 10^{- 3} S^{- 1}$

9. For the reaction, 2A $\to$ B + C,a plot of log [A] $υ s$ time is found to be a straight line.The order of the reaction must be

a)		One
b)		Zero
c)		Two
d)		Three

10. $t_{1 / 2}$ of first order reactions is given by $\frac{0.693}{k}, t_{3 / 4}$ would be equal to

a)		$\frac{0.693}{k}$
b)		$\frac{0.346}{k}$
c)		$\frac{1.386}{k}$
d)		$\frac{0.924}{k}$

11. For a first order reaction. $t_{0.75}$ is 1386 seconds.Therefore,the specific rate constant is

a)		$10^{- 1} s^{- 1}$
b)		$10^{- 3} s^{- 1}$
c)		$10^{- 2} s^{- 1}$
d)		$10^{- 4} s^{- 1}$

12. The value of activation energy is primarily determined by

a)		temperature
b)		collision frequency
c)		concentration of reactant
d)		chemical nature of reactants and products

13. Consider a gaseous reaction having rate expression as rate=k[A] [B $]^{2}$ .If volume of the vessel is suddenly reduced to half the initial volume,the rate of the reaction would become .....times the original rate.

a)		3
b)		2
c)		1/2
d)		8

14. Which of the following is an acceptable value of molecularity?

a)		5
b)		0
c)		3/2
d)		2

15. For a zero order reaction involving gaseous species,the rate of the reaction changes with change in

a)		Concentration
b)		pressure
c)		volume
d)		temperature

16. The dimentions of rate constant for a first order reactrion involve

a)		Time and concentration
b)		Time only
c)		Concentration only
d)		Neither time nor concentration

17. For chemical reaction A $\to$ B,it is found that the rate of reaction doubles when the concentration of A is increased four times.The order of the reaction is

a)		4
b)		2
c)		1
d)		1/2

18. The half life of a $1^{st}$ order reaction is 46.2 ${mm}^{- 1}$ .The value of rate constant of the reaction is

a)		1.05 ${mm}^{- 1}$
b)		0.15 ${mm}^{- 1}$
c)		0.015 ${mm}^{- 1}$
d)		0.0015 ${mm}^{- 1}$

19. If the half-life for ${}^{14}C$ is 5760 years,then $t_{3 / 4}$ is

a)		5760 $\times$ 1years
b)		5760 $\times$ 3/4years
c)		5760 $\times$ 2years
d)		5760 $\times$ 4/3years

20. For an exothermic reaction temperature increase by $10^{0} C,$ the equillibrium will be attained faster

a)		2 times
b)		same
c)		1/2 times
d)		4 times

21. On addition of one ml solution of 10% NaCl to 10 ml gold solution in the presence of 0.025 g of starch, the coagulation is prevented because starch has the following gold numbers

a)		25
b)		0.025
c)		0.25
d)		2.5

22. For the reaction 2A+B $\to C + D,$ measurement of the rate of the reaction at varying concentrations are given below
$\begin{matrix} Trial No . & [A] & [B] & rate (mmol L^{- 1} S^{- 1}) \\ 1 & 0.010 & 0.010 & 2.5 \\ 2 & 0.010 & 0.020 & 5.0 \\ 3 & 0.030 & 0.020 & 45.0 \end{matrix}$
The rate law is therefore

a)		rate = K ${[A]}^{2} [B]$
b)		rate = K $[A] {[B]}^{2}$
c)		rate =K $[A] [B]$
d)		rate =K ${[A]}^{2} {[B]}^{2}$

23. A first order reaction was started with a decimolar solution of the reactant. 8 minutes and 20 seconds later its concentration was found to be M/100. So the rate constant of the reaction is

a)		2.303 $\times 10^{- 5} \sec^{- 1}$
b)		2.303 $\times 10^{- 4} \sec^{- 1}$
c)		4.606 $\times 10^{- 3} \sec^{- 1}$
d)		2.606 $\times 10^{- 5} \sec^{- 1}$

24. The coagulating power of an electrolyte for arsenious sulphide decreases in the order

a)		${Na}^{+} > A l^{3} + > B a^{2 +}$
b)		P $O_{4}^{- 3} > S O_{4}^{2} > Cl$
c)		Cl $> S O_{4}^{2} > P O_{4}^{3}$
d)		A $l^{3 +} > B a^{2 +} > N a^{+}$

25. Which of the following statement is not correct?

a)		In zero order reaction the rate of the reaction remains constant throughout
b)		A second order reaction would become a pseudo first order reactin when one of the reactants is taken in large excess
c)		The value of first order rate constant depends on the the units of the concentration terms used
d)		In a first order reaction the plot of log (a-x)Vs times gives a straight line

26. The volumes of gases $H_{2,}$ C $H_{4}, C O_{2}$ and N $H_{3}$ absorbed by 1 gm of activated charcoal at 298 are in the order

a)		$H_{2} > C H_{4} > C O_{2} > N H_{3}$
b)		C $H_{2} > C O_{2} > N H_{3} > H_{2}$
c)		N $H_{3} > C O_{2} > C H_{4} > H_{2}$
d)		${CO}_{2} > N H_{3} > C H_{4} = H_{2}$

27. The time taken for the completion of 3/4 of a first order reaction is

a)		(2.303/k)log 3/4
b)		(2.303/k)log4
c)		(2.303/0.75)log K
d)		(2.303/0.75)log K

28. A chemical reaction was carried out at 300K and 280K. The rate constants were found to be $k_{1}$ and $k_{2}$ respectively. Then

a)		$k_{2} = 4 k_{1}$
b)		$k_{2} = 2 k_{1}$
c)		$k_{2} = 0.25 k_{1}$
d)		$k_{2} = 0.5 k_{1}$

29. The activation energy of a reaction can be determined by

a)		changing the concentration of reactants
b)		evaluating the rate constant at standard temperature
c)		evaluating rate constant at two different temperature
d)		by doubling concentration reactants

30. Velocity constant of a reaction at 290 K was found to be 3.2 $\times 10^{- 3} .$ At 300K it will be

a)		1.28 $\times 10^{- 2}$
b)		9.6 $\times 10^{- 3}$
c)		6.4 $\times 10^{- 3}$
d)		3.2 $\times 10^{- 4}$

31. For a chemical reaction A $\to B,$ it is found that the rate of reaction doubles when the concentration of A is increased four times. The order in A for this reaction is

a)		Two
b)		One
c)		Half
d)		Zero

32. Rate constant in case of first order reaction is

a)		Inversely proportional to the concentration units
b)		Independent of concentration units
c)		Directly proportional to the concentration units
d)		Inversely proportional to the square of the concentration units

33. If initial concentration of reactants in certain reaction is doubled, the half life period of the reaction doubles, the order of reaction is

a)		Zero
b)		First
c)		Second
d)		Third

34. The rate of reaction, A+B $\to$ products is given by the equation r = K $[A] [B] .$ If B is taken in large excess, the order of the reaction would be

a)		2
b)		1
c)		0
d)		unpredictable

35. For most of the chemical reactions the rate of reaction

a)		Increases as the reaction proceeds
b)		Decreases as the reaction proceeds
c)		May increase or decrease during the process
d)		Remains constant as the reaction proceeds

36. The decomposition of a substance follows first order kinetics. If its conc. Is reduced to $\frac{1}{8^{th}}$ of its initial value, in 24 minutes, the rate constant of decomposition process is

a)		$\frac{1}{24} \min^{- 1}$
b)		$\frac{0.692}{24} \min^{- 1}$
c)		$\frac{2.303}{24} {\log (1 / 8) \min}^{- 1}$
d)		$\frac{2.303}{24} {\log (8 / 1) \min}^{- 1}$

37. The order of reaction is decided by

a)		temperature
b)		mechanism of reaction as well as relative concentration of reactants
c)		molecularity
d)		pressure

38. The half life period for a first order reaction is 693 seconds. The rate constant of this reaction would be

a)		0.1 $\sec^{- 1}$
b)		0.001 $\sec^{- 1}$
c)		0.01 $\sec^{- 1}$
d)		0.0001 $\sec^{- 1}$

39. The time taken for 90% of a first order reaction to complete is approximately

a)		1.1 times of that of half life
b)		2.2 times of that of half life
c)		3.3 times of that of half life
d)		4.4 times of that of half life

40. 75% of first order reaction is complete in 30 minutes. What is the time required for 93.75% of the reaction (in minutes) ?

a)		45
b)		120
c)		90
d)		60

41. If reaction between A and B to give C shows first order kinetics in A and second order in B, the rate equilibrium can be written as

a)		Rate =k[A][B $]^{\frac{1}{2}}$
b)		Rate =k[A $]^{\frac{1}{2}}$ [B $]$
c)		Rate =k[A][B $]^{2}$
d)		Rate =k[A $]^{2}$ $[B]$

42. The Arrhenius equation expressing the effect of temperature on the rate constant of the reaction is

a)		k = e $\frac{Ea}{RT}$
b)		k = $\frac{Ea}{RT}$
c)		k = lo $g_{e}$ $\frac{Ea}{RT}$
d)		k = A. $e^{\frac{{- E}_{a}}{RT}}$

43. The reaction $N_{2} O_{5} (in cc l_{4}) \to {2 NO}_{2} + \frac{1}{2} O_{2} (g)$ is the first order in $N_{2} O_{5}$ with rate constant 6.2 x $10^{- 4} s^{- 1} .$ What is the value of rate of reaction when[ $N_{2} O_{5}] = 1.25 mol L^{- 1}$ ?

a)		7.75 x $10^{- 4}$ mol $L^{- 1} s^{- 1}$
b)		6.35 x $10^{- 3}$ mol $L^{- 1} s^{- 1}$
c)		5.15 x $10^{- 5}$ mol $L^{- 1} s^{- 1}$
d)		3.85 x $10^{- 4}$ mol $L^{- 1} s^{- 1}$

44. For a reaction of type A+B $\to$ products, it is observed that doubling concentration of A cause the reaction rate to be four times as great, but doubling amount of B does not affect the rate. The rate equation is

a)		Rate =K[A][B]
b)		Rate = $\frac{k}{4} [A]^{2}$
c)		Rate = K[A $]^{2} [B]^{0}$
d)		Rate = K[A $]^{2} [B]^{2}$

45. For the first order reaction with rate constant k, which expression gives the half life period? (initial conc = a)

a)		$\frac{in 2}{ka}$
b)		$\frac{1}{ka}$
c)		$\frac{0.693}{k}$
d)		$\frac{3}{{2 ka}^{2}}$

46. A chemical reaction is catalysed by X. Hence X

a)		does not affect equilibrium constant of the reaction
b)		decrease rate constant of the reaction
c)		decrease enthalpy of reaction
d)		increases activation energy of the reaction

47. The reaction ${2 H}_{2} O_{2} + O_{2}$ is r =k[ $H_{2} O_{2}]$

a)		Zero order reaction
b)		First order reaction
c)		Second order reaction
d)		Third order reaction

48. The rate of constant of first order reaction whose half life is 480 sec is

a)		1.44 x $10^{- 3} \sec^{- 1}$
b)		1.44 $\sec^{- 1}$
c)		0.72 x $10^{- 3} \sec^{- 1}$
d)		2.88 x $10^{- 3} \sec^{- 1}$

49. A reaction A $\to B$ follows a second order kinetics . Doubling the concentration of A will increase the rate of formation of B by a factor of

a)		2
b)		$\frac{1}{2}$
c)		4
d)		$\frac{1}{4}$

50. If the concentration is expressed in moles per litre, the unit of the rate constant for a first order reaction is

a)		${mol litre}^{- 1} \sec^{- 1}$
b)		${mol litre}^{- 1}$
c)		$\sec^{- 1}$
d)		${mol}^{- 1}$