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Chemistry

Chemical Kinetics

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1
In which of the following half life of a reaction does not depends on initial concentration?
A
zero order reaction
B
first order reaction
C
second order reaction
D
third order reaction
2
For the reaction, A + B → C + D, the rate expression is R = k[A]²[B]. If the concentration of both the reactants is doubled then the rate of reaction will be;
A
quadruple
B
double
C
eight times
D
triple
3
Given below are two statements: Statement I: Catalyst increases the rate of reaction by decreasing the activation energy. Statement II: The reaction taking place in one step is known as elementary reaction.
A
Statement I is correct but Statement II is incorrect.
B
Statement I is incorrect but Statement II is correct.
C
Both Statement I and Statement II are correct.
D
Both Statement I and Statement II are incorrect.
4
The rate of reaction decreases by factor 4 when [B] doubled. Order w.r.t B is:
A
2
B
–2
C
1
D
–1
5
The integrated rate equation is given below, kt = log C0 – log Ct / 2.303. The straight line graph is obtained by plotting:
A
time vs logCt
B
1/time vs Ct
C
time vs Ct
D
1/time vs 1/Ct
6
Given below are two statements: Statement I: For a zero-order reaction A → B, successive half-life decreases with progress of reaction. Statement II: Rate of zero-order reaction remains unchanged with progress of reaction.
A
Statement I is correct but Statement II is incorrect.
B
Statement I is incorrect but Statement II is correct.
C
Both Statement I and Statement II are correct.
D
Both Statement I and Statement II are incorrect.
7
A first order reaction has a rate constant 1.15 × 10⁻³ s⁻¹. How long will 5 g of the reactant takes to reduce to 2 g? [log5 = 0.7, log2 = 0.3]
A
200 s
B
400 s
C
800 s
D
1600 s
8
The half-life of first order reaction is 25 min. Rate constant is:
A
2.27 × 10–2 min–1
B
3.2 × 10–2 min–1
C
9.2 × 10–2 min–1
D
2.8 × 10–2 min–1
9
Given below are two statements: Statement I: Molecularity does not influence rate. Statement II: Rate governed by slowest step.
A
I correct II incorrect
B
I incorrect II correct
C
Both correct
D
Both incorrect
10
What will be the half-life of the first order reaction for which the value of rate constant is 100 s–1?
A
693 × 10–5 s
B
6.93 × 10–5 s
C
69.3 × 10–5 s
D
0.693 × 10–5 s
11
How much time is required to complete 90% of a first order reaction?
A
2.303 k
B
2.303/k
C
k/2.303
D
0.693/k
12
A
B
C
D
13
In the Arrhenius equation, the fraction of effective collisions is given by:
A
Ae–Ea/R
B
A
C
e–Ea/RT
D
RT
14
The catalytic activity of the transition metals and their compounds is described to :
A
their chemical reactivity.
B
their magnetic behaviour.
C
their unfilled d-orbitals
D
their ability to adopt multiple oxidation state and their complexing ability.
15
What is the effect of raising the temperature on the Maxwell-Boltzmann distribution curve?
A
Fewer molecules have higher energy
B
Curve becomes narrower
C
More molecules have higher energy
D
Curve shifts to lower energy
16
The correct relation for rate constant (k) at two different temperatures among the following is;
A
log(k2/k1) = Ea/2.303 (1/T1 – 1/T2)
B
log(k2/k1) = Ea/2.303R (1/T1 – 1/T2)
C
log(k1/k2) = Ea/2.303 (1/T2 – 1/T1)
D
log(k1/k2) = Ea/2.303R (1/T2 – 1/T1)
17
Consider the first-order decomposition reaction A4(g) → 4A(g). Which statement is correct?
A
10% complete at 30 min
B
t1/2 = 60 min
C
Rate decreases linearly
D
Time independent of initial concentration
18
If the rate of reaction X → Y doubles on increasing the concentration of X by eight times, the order of reaction is:
A
3
B
1/3
C
8
D
1/8
19
Given below are two statements: Statement I: Order of reaction can have fractional values. Statement II: Molecularity of a reaction is always a positive integer.
A
Statement I is correct but Statement II is incorrect.
B
Statement I is incorrect but Statement II is correct.
C
Both Statement I and Statement II are correct.
D
Both Statement I and Statement II are incorrect.
20
A
B
C
D
21
Which of the following relation for t1/2 and a is correct for zero order reaction?
A
t1/2 ∝ a
B
t1/2 ∝ 1/a
C
t1/2 ∝ 1/a³
D
t1/2 ∝ 1/a⁴
22
The rate constant for a first order reaction is 4.606 × 10–3 s–1. Time required to reduce 2.0 g to 0.2 g is:
A
200 s
B
500 s
C
1000 s
D
100 s
23
Collision theory explains rate. Which does NOT influence rate?
A
Temperature
B
Orientation
C
Velocity
D
All influence
24
If ‘ao’ is the initial concentration and ‘n’ is the order of the reaction then half life time ‘t1/2’ can be expressed as;
A
t1/2 ∝ (a0)^n
B
t1/2 ∝ (a0)^–n
C
t1/2 ∝ (a0)^(1–n)
D
t1/2 ∝ (a0)^(1+n)
25
A
B
C
D
26
The rate constant k1 and k2 for two reactions are given. The temperature at which k1 = k2 is:
A
1000 K
B
2000 K / 2.303
C
2000 K
D
1000 K / 2.303
27
The rate constants of a reaction at 500 K and 600 K are 0.02 s⁻¹ and 0.04 s⁻¹ respectively. The value of activation energy is
A
17.3 kJ mol⁻¹
B
24.2 kJ mol⁻¹
C
8.2 kJ mol⁻¹
D
28.2 kJ mol⁻¹
28
For the reaction X → Y + Z, the rate constant is 0.00058 s–1. What percentage of X will be decomposed in 50 minutes?
A
90.02 %
B
82.44 %
C
88.82 %
D
82.67 %
29
The rate constant for a reaction is 1.5 × 10–4 mol L–1 s–1. The order of the reaction is;
A
zero
B
first
C
second
D
third
30
Which statement is correct about half-life period?
A
Proportional to initial concentration (zero order)
B
Used to determine order
C
Independent of concentration (first order)
D
Catalyst does not affect half-life
31
A
B
C
D
32
For an endothermic reaction, minimum value of Ea will be;
A
less than ΔH
B
equal to ΔH
C
more than ΔH
D
zero
33
If the rate of reaction is expressed as follows: Rate = 1/2 d[C]/dt + 1/3 d[D]/dt = –1/4 d[A]/dt = – d[B]/dt Then the reaction is:
A
4A + B → 2C + 3D
B
B + 3D → 4A + 2C
C
A + B → C + D
D
B + D → A + C
34
For the reaction, P + Q → PQ, the following data is obtained. The overall order of the reaction is:
A
2
B
0
C
1
D
3
35
For reaction 2A → B, correct relation is:
A
–2 d[A]/dt = 1/2 d[B]/dt
B
2 d[A]/dt = –1/2 d[B]/dt
C
–1/2 d[A]/dt = d[B]/dt
D
1/2 d[A]/dt = –d[B]/dt
36
A
B
C
D
37
A
B
C
D
38
A
2
B
0
C
3
D
1
39
A first-order reaction is 25% complete in 30 minutes. What is the half-life of the reaction?
A
40.2 min
B
66.3 min
C
83.1 min
D
90.4 min
40
Select the incorrect statement(s):
A
Elementary reactions are single step reactions
B
Reaction kinetics governed by slowest step
C
Order of a reaction cannot be 1/2
D
Order of reaction is experimental
41
Which one of the following reaction is an example of psedo first order reaction?
A
acidic hydrolysis of ester
B
thermal decomposition of HI on gold surface
C
decomposition of gaseous ammonia on hot platinum
D
hydrogenation of ethene
42
All natural radioactive decay of unstable nuclei takes place by:
A
first order kinetics
B
second order kinetics
C
zero order kinetics
D
third order kinetics
43
Activation energy depends upon:
A
Temperature
B
Nature of reacting species
C
Concentration
D
Collision frequency
44
Given below are two statements: Assertion: Catalyst does not change activation energy Reason: Lower activation energy → faster reaction
A
A true R false
B
A false R true
C
Both true and R explains
D
Both true not explanation
45
According to collision theory, conditions for successful reaction are: 1. Sufficient energy 2. Catalyst presence 3. Proper orientation
A
1,2,3
B
1 only
C
1 and 3
D
2 and 3
46
Given below are two statements: Statement I: For a zero order reaction, the rate of reaction does not depend on initial concentration of reactant. Statement II: Order and molecularity are always equal in elementary reaction.
A
Statement I is correct but Statement II is incorrect.
B
Statement I is incorrect but Statement II is correct.
C
Both Statement I and Statement II are correct.
D
Both Statement I and Statement II are incorrect.
47
If the rate constant for first-order reaction is k, time required for 99% completion is;
A
2.303/k
B
0.693/k
C
4.606/k
D
6.909/k
48
The hydrolysis of methyl formate in acid solution has the rate expression rate = K[HCOOCH3][H+]. The rate law contains [H+] though the balanced equation does not contain H+ because;
A
more for convenience
B
H+ is a catalyst
C
H+ is always present
D
all acids contain H+
49
Given below are two statements: Assertion (A): Rate of reaction increases with increase in temperature. Reason (R): Number of effective collisions increases with increase in temperature.
A
A is correct but R is incorrect.
B
A is incorrect but R is correct.
C
Both A and R are correct.
D
Both A and R are incorrect.
50
Slope of a plot between log([R]0/[R]) vs time for a first order reaction is:
A
k/2.303
B
–k/2.303
C
–2.303/k
D
2.303/k
51
The rate constant of a reaction has unit mol–1 L s–1. What is the order of reaction?
A
2
B
1
C
0
D
3
52
Threshold energy of a reaction is equal to;
A
Activation energy – Energy possessed by reacting species.
B
Activation energy + Energy possessed by reacting species.
C
Energy possessed by reacting species – Activation energy.
D
Energy possessed by reacting species + Activation energy
53
The rate constant for a first order reaction is 2.303 × 10–2 s–1. The time required to reduce 4 g of the reactant to 2 g is;
A
25.12 s
B
36.41 s
C
30.09 s
D
18.71 s