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Published on: 02/11/2025
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Questions + Answers key
Take MCQ Chemistry Test
1.
The following experimental rate data were obtained for a reaction carried out at 25C
A(g)+ B(g) → C(g)+ D(g)
What are the orders with respect to A(g) and B(g)?
| Order with respect to A(g) | Order with respect to B(g) |
| Zero | Second |
| Order with respect to A(g) | Order with respect to B(g) |
| First | Zero |
| Order with respect to A(g) | Order with respect to B(g) |
| Second | Zero |
| Order with respect to A(g) | Order with respect to B(g) |
| Second | First |
2.
The rate of a reaction increases sixteen times when the concentration of the reactant increases four times.The order of the reaction is
2.5
2.0
1.5
0.5
3.
In Arrhenius plot of Ink Vs \(\frac{1}{\mathrm{~T}}\) is a linear plot obtained with slope of -2 x 104 k. Ea of reaction in kJ mol -1.
83
166
249
332 kJ mol -1
4.
Consider Fig. and mark the correct option.
Activation energy of forward reaction is E1 + E2 and product is less stable than reactant.
Activation energy of forward reaction is E1 + E2 and product is more stable than reactant.
Activation energy of both forward and backward reaction is E1 + E2 and reactant is more stable than product.
Activation energy of backward reaction is E1 and product is more stable than reactant.
5.
In the first order reaction the concentration of reactant decreases from 0.6 M to 0.3 M in 30 minutes. The time taken for the concentration to change from 0.1 M to 0.025 M:
60 min
30 min
15 min
50 min
6.
If conc. of reactant' A' is increased 10 times and rate of reaction becomes 100 times. What is order with respect to 'A'?
1
2
3
4
7.
For a reaction taking place in three steps, the overall rate constant k \(=\frac{k_{1} k_{2}}{k_{3}}\) If Ea1, Ea2 and Ea3 are the 40, 50 and 60 kJ mol-1, the overall Ea is
30
40
60
50
8.
If the initial concentration of reactant is doubled, t1/2 is also doubled, the order of reaction is
zero
1
2
3
9.
The rate of first order reaction is 0.04 mol L-1 s-1 at 10 sec. and 0.03 mol L-1 at 20 seconds after initiation of the reaction. t1/2 of reaction is
44.1 s
54.1 s
24.1 s
34.1 s
10.
The rate constant of a reaction A \(\rightarrow\) B is 0.6 x 10- 3 mole per second. If the concentration of [A] is 5 M, then what will be concentration of [B] after 20 months?
0.36 M
0.72 M
1.08 M
3.60 M
11.
The half life period of first order reaction is 1386 seconds. The specific rate constant ofthe reaction is
0.5 x 10- 2 s-1
0.5 x 10- 3 s-1
5.0 x 10- 2 s-1
5.0 x 10-3 S-1
12.
According to Arrhenius equation rate constant k is equal to A e.-Ea/RT Which of the following options represents the graph of In k vs 1/T
13.
Arrhenius equation may not be represented as
\( \ln \frac{A}{k}=\frac{E_{a}}{R T}\)
\(K=Ae^-Ea/RT\)
\(\log A=\log k+\frac{E_{\alpha}}{2303 R T}\)
\(\log k-\left(\frac{E_{a}}{R T}\right)=A\)
14.
The temperature coefficient of a reaction is
the ratio of rate constant at two temperatures
the ratio of rate constant differing by 10o preferably 25oC and 35oC
the rate constant at a fixed temperature
None of the above
15.
For the reaction,
half-life does not depend on the concentration of the reactant. After 10 min, volume of N2 gas is 20 L and after the completion of reaction, it is 100 L. Hence, rate constant is
\(\frac{2.303}{10}\) log 5 min-1
\(\frac{2.303}{10}\) log 10 min-1
\(\frac{2.303}{10}\) log 10 min-1
\(\frac{2.303}{10}\) log 20 min-1
16.
Four reactions are given below. Which one of them is of zero order?
\(\mathrm{PCL}_{5} \longrightarrow \mathrm{PCl}_{3}+\mathrm{Cl}_{2}\\ \)
\( 2 \mathrm{FeCl}_{\mathrm{s}}+\mathrm{SnCl}_{2} \longrightarrow 2 \mathrm{FeCl}_{2}+\mathrm{SnCl}_{4}\\ \)
\( \mathrm{H}_{2}+\mathrm{Cl}_{2} \longrightarrow 2 \mathrm{HCl}\\ \)
\( \mathrm{N}_{2} \mathrm{O}_{5} \longrightarrow 2 \mathrm{NO}_{2}+\frac{1}{2} \mathrm{O}_{2}\\\)
17.
When the rate of reaction is independent of the concentration of reactants, then the order of that chemical reaction is
one
two
three
zero
18.
Find the order of the reaction whose rate constant is 2.5 x 10-2 min-1
zero
three
two
one
19.
During a chemical reaction with increase in temperature, rate of a reaction
decreases
increases
remains constant
show irregular trends
20.
The factors affecting the rate of a reaction are
temperature
pressure
concentration of reactant or product
catalyst
21.
In a reaction, 2x ⟶ y, the concentration of x decreases from 3.0 M to 1.5 Min 4 min. The rate of the reaction is
0.187 M min-1
1.87 M min-1
3.75 x 10-1M min-1
0.75 M min-1
22.
Rate of which of the following reactions can be determined easily?
Rusting of iron in the presence of air and moisture
Hydrolysis of starch
Reaction of silver nitrate with sodium chloride
All of the above
23.
A catalyst
increases the average kinetic energy of the reacting molecules.
decreases the activation energy
alters the reaction mechanism
increaes the frequency of collision of the reacting species
24.
In a hypothetical reaction X \(\longrightarrow\) Y, the activation energy for the forward and the backward reaction are 15 and 9 kJ mol-1 respectively. The potential energy of X is 10 kJ mol-1. Then
Threshold energy of the reaction is 25 kJ
The potential energy of Y is 16 kJ
Heat of reaction is 6 kJ
The reaction is endothermic
25.
The initial rate hydrolysis of methyl acetate (1 M) by a week acid (HA, 1 M) is 1/100th of that of a strong acid (HX, 1 M) at 25oC. The ka of HA is
1 \(\times 10 ^{-4}\)
1\(\times 10 ^{-5}\)
1\(\times 10 ^{-6}\)
1\(\times 10 ^{-3}\)
26.
For first reaction A \(\longrightarrow\) P, the temperature (T) dependent rate constant (k) was found to follow the equation log k = -(2000)\(\frac {1}{T}\) +6.0.
The pre-exponential factor A and the activation energy Ea respectively, are
1.0 \(\times 10^{6}s^{-1}\) and 9.2 kJ mol -1
6.0 \(s^{-1}\) and 16.6 kJ mol -1
1.0 \(\times 10^{-1}s^{-1}\) and 16.6 kJ mol -1
1.0 \(\times 10^{6}s^{-1}\) and 38.3 kJ mol -1
27.
The rate constants k1 and k2 for two different reactions are 1016. e-2000/T and 1015. e-1000/T respectively. The temperature at which k1 = k2 is
1000 K
\(\frac {2000}{2.303}K\)
2000 K
\(\frac {1000}{2.303}K\)
28.
When a catalyst increase the rate of a chemical reactiom, the rate constant
remains constant
increases
decreases
decrease depending on the order of reaction.
29.
For an endothermic reaction, where \(\triangle H\) represents the enthalpy of the reaction in kJ/mol. The minimum value for the energy of activation will be
less than \(\triangle H\)
zero
more than \(\triangle H\)
equal to \(\triangle H\)
30.
H2O2 is formed in the upper atmosphere through the following mechanism
H2O + (O) \(\longrightarrow\) 2OH \(\longrightarrow\) H2O2
The overall enthalpy change and activation energy for the forward reaction are 72 kJ mol-1 and 77 kJ mol-1 respectively. The activation energy for the decomposition of H2O2 to give back H2O and (O) will be
5 kJ mol-1
-5 kJ mol-1
149 kJ mol-1
-149 kJ mol-1
31.
The rate constant of reaction at temperature 200 K is 10 times less than the rate constant at 400 K. what is the activation energy of the reaction ?
1842.4 R
921.2 R
460.6 R
230.3 R
32.
A reactant (A) forms two products:
A \(\xrightarrow { { k }_{ 1 } } \) B, Activation Energy \({ E }_{ { a }_{ 1 } }\)
A \(\xrightarrow { { k }_{ 1 } } \) C, Activation Energy \({ E }_{ { a }_{ 2 } }\)
If \({ E }_{ { a }_{ 2 } }\) = 2\({ E }_{ { a }_{ 1 } }\) , then k1 and k2 are related as
k1 = 2k2 \({ e }^{ { Ea }/_{ 2 }RT }\)
k2 = k1 \({ e }^{ { Ea }/_{ 2 }RT }\)
k2 = k1 \({ e }^{ { Ea }/_{ 2 }RT }\)
k1 = Ak2\({ e }^{ { Ea }/_{ 2 }RT }\)
33.
The rate of a reaction doubles when its temperature changes from 300 K to 310 K activation energy of such a reaction will be
60.5 kJ mol-1
53.6 kJ mol-1
48.6 kJ mol-1
58.5 kJ mol-1
34.
For a first order reaction, tav (average life time), t50% and t75% are in the order :
t50 < tav < t75
t50 < t75 < tav
tav < t50 < t75
tav < t50 < t75
35.
For the elementary reaction M \(\longrightarrow\) N, the rate of disappearance of M increses by a factor of 8 upon doubling the concentration of M. The order of reaction with respect to M is
4
3
2
1
36.
For the non-stoiciometric reaction :
2 A + B \(\longrightarrow\) C + D, the following kinetic data were obtained in three separate experiments all at 298 K
|
Initial concentration [A] |
Initial concentration [B] |
Initial rate of formation of C (mol L-1 s-1) |
|---|---|---|
| 0.1 M | 0.1 M | 1.2 \(\times 10^{-3}\) |
| 0.1 M | 0.2 M | 1.2\(\times 10^{-3}\) |
| 0.2 M | 0.1 M | 2.4\(\times 10^{-3}\) |
\(\frac {dC}{dt} = k[A]\)
\(\frac {dC}{dt} = k[A] [B]\)
\(\frac {dC}{dt} = k[A]^{2} [B]\)
\(\frac {dC}{dt} = k[A] [B]^{2}\)
37.
Kinetics of the reaction A (g) \(\longrightarrow\) 2 B (g) + C (g) is followed by measuring the total pressure at different times. It is given that
Initial pressure of A = 0.5 atm.
Total pressure of A after 2 hours = 0.7 atm
Rate constant of the reaction = 1 \(\times 10 ^{-3}s^{-1}\)
What is the rate of reaction \(-\frac {d[A]}{dt}\) when the total pressure is 0.7 atm?
2.0 \(\times 10^{-4}M s^{-1}\)
4.0\(\times 10^{-4}M s^{-1}\)
5.0\(\times 10^{-4}M s^{-1}\)
7.0\(\times 10^{-4}M s^{-1}\)
38.
For a second order reaction, 2 A \(\longrightarrow\) Products, a plot of log t 1/2 vs log a (where a is the initial concentration) will give an intercept equal to which of the following ?
1/k
log (1/2 k)
log (1/k)
log k
39.
Te half-life of a reaction is halved as the initial concentration of the reactant is doubled. The order of reaction is
0.5
1
2
0
40.
For a first order reaction, the time required for 99.9% of the reaction to take place is nearly
10 times that required for half of the reaction
100 times that required for two - thirds of the reaction
10 times that required forone - fourth of the reaction
20 times that required for half of the reaction
41.
For a reaction A + B \(\longrightarrow\) product, rate law is \(-\frac { d[A] }{ dt } =k[{ A }]_{ 0 }\) The concentration of X changes from 0.1 M to 0.025 M, then the rate of reaction when concentration of X is 0.01 M is
1.73 \(\times 10 ^ {-4} M/min\)
3.47\(\times 10 ^ {-5} M/min\)
3.47\(\times 10 ^ {-4} M/min\)
1.73\(\times 10 ^ {-5} M/min\)
42.
t1/4 can be taken as the time taken for the concentration of a reactant to drop to \(\frac {3}{4}\) of its initial value. If the rate constant for a first order reaction is K, then t1/4 can be written as
0.10/K
0.29/K
0.69/K
0.75/K
43.
A relation P \(\longrightarrow\) Q is completed 25 % in 25 min 50 % completed in 25 min if [P] is halved, 25% completed in 50 min if [P] is doubled. The order of reaction is
1
2
0
3
44.
At 500 K, the half-life period of a gaseous reaction at the initial pressure of 80 kPa is 350 sec. When the pressure is 40 kPa, the half-life period is 175 sec. The order of reaction is
second
more than zero but less than first
zero
first
45.
For the reaction A + 2 B \(\longrightarrow\) C, the reaction rate is doubled if the increased by four times when concentration of both A and B are increased by four times. The order of reaction is
3
0
1
2
46.
The following data is obtained during the first order thermal decomposition of 2 A (g) \(\longrightarrow\) B (g) + C (s) at constant volume and temperature
| S. No. | Time | Total Pressure in pascals |
|---|---|---|
|
1. 2. |
At the end of 10 minutes After completion |
300 200 |
The rate constant in min -1 is
0.0693
6.93
0.00693
69.3
47.
The time taken for 10% completion of a first order reaction is 20 min. Then for 19% completion, the reaction will take
40 mins
60 mins
30 mins
50 mins
48.
Half -lives of a first order and a zero order reaction are same. Then the ratio of the initial rates of the first order reaction to that of zero order reaction is
\(\frac {1}{0.693}\)
2\(\times\) 0.693
0.693
\(\frac {2 }{0.693}\)
49.
A first order reaction is carried out staring with 10 mol L-1 of the reactant. It is 40 % complete in one hour. If the same reaction is carried out with an initial concentration of 5 mol L-1, the percentage of the reaction that is completed in one hour will be
40 %
80 %
20 %
60 %
50.
The rate of the reaction A \(\longrightarrow\) Products, at the initial concentration of 3.24 \(\times 10^{-2}M\) is nine times its rate at another initial concentration of 1.2 \(\times 10^{-3}M\) . The order of the reaction is
\(\frac {1}{2}\)
\(\frac {3}{4}\)
\(\frac {3}{2}\)
\(\frac {2}{3}\)
\(\frac {1}{3}\)
51.
Higher order (>3) reactions are rare due to
Low probability of simulateous collision of all the reacting species
Increase in entropy and activation energy as more molecules are involved
shifting of equlibrium towards reactants due to elastic collisions
loss of active species on collision
52.
The rate of a gaseous reaction is generally expressed in terms of \(\frac {dP}{dt}\). If it were expressed in terms of change in number of moles per unit time \((\frac {dn}{dt})\) or in terms of change in molar concentration per unit time \((\frac {dC}{dt}),\) which of the following relationship will hold good ?
\(\frac { dC }{ dt } =\frac { dn }{ dt } =\frac { dP }{ dt } \)
\(\frac { dC }{ dt } =\frac{1}{V}(\frac { dn }{ dt }) =\frac{1}{RT}(\frac { dP }{ dt }) \)
\(\frac { dC }{ dt } =\frac { dn }{ dt } =\frac{1}{RT}(\frac { dP }{ dt }) \)
None of these
53.
In the graph showing Maxwell Boltzman distribution of energy, ....... .
area under the curve must not change with increase in temperature
area under the curve increases with increase in temperature
area under the curve decreases with increase in temperature
with increase in temperature curve broadens and shifts to the right hand side.
54.
According to Maxwell Boltzmann distribution of energy, ....... .
the fraction of molecules with most probable kinetic energy decreases at higher temperatures
the fraction of molecules with most probable kinetic energy increases at higher temperatures
most probable kinetic energyincreases at higher temperatures
most probable kinetic energy decreasesat higher temperatures.
55.
During decomposition of an activated complex
energy is always realeased
energy is always absorbed
energy is not change
reaction may be formed
56.
Which of the following statements are applicable to a balanced chemical equation of an elementary reaction ?
Order is same as molecularity
Order is less than the molecularity
Order is grater than the molecularity
Molecularity can never be zero.
57.
The value of rate constant of a pseudo first order reaction ............... .
depends on the concentration of reactants present in small amount
depends on the concentration of reactants present in excess
is independent of the concentration of reactants
depends only on temperature.
58.
Which of the following statement is not correct for the catalyst ?
It catalyses the forward and backward reaction to the same extent
It alters \(\triangle G\) of the reaction
It is a substance that does not change the equilibrium constant of a reaction
It proivides an alternate machanism by reducing activation energy between energy between reactants and products.
59.
Compounts 'A' and 'B' react according to the following chemical equation :
A (g) + 2 B (g) \(\longrightarrow\) 2 C (g)
Concntration of either 'A' or 'B' were changed keeping the concentration of the reactions constant and rates were measured as a function of initial concentration. Following results were obtained. Choose the correct option for the rate equations for this reaction.
| Exp. |
Initial |
Initial |
Initial rate of |
|---|---|---|---|
| 1. | 0.30 | 0.30 | 0.10 |
| 2. | 0.30 | 0.60 | 0.40 |
| 3. | 0.60 | 0.30 | 0.20 |
Rate = k[A]2[B]
Rate = k[A] [B] 2
Rate = k[A] [B]
Rate = k[A]2 [B] 0
60.
A first order reaction is 50% completed in 1.26\(\times 10^{15} s\) . How much time would it take for 100% completion ?
1.26 \(\times 10^{15} s\)
2.52 \(\times 10^{14} s\)
2.52 \(\times 10^{28} s\)
infinite
61.
Rate law for the reaction A + 2B \(\longrightarrow\) C is found to be Rate = k [A] [B] Concentration of reactant 'B' is doubled, keeping the concentration of 'A' constant, the value of the rate constant will be ............. .
the same
doubled
quadrupled
halved
62.
Which of the following expressions is correct for the rate of reaction given below ?
5Br- (aq) + BrO-3 (aq) + 6H+ (aq) \(\longrightarrow\) 3Br2 (aq) + 3H2O(I)
\(\frac {\triangle [Br^{-}]}{\triangle t} = 5\frac {\triangle [H^{+}]}{\triangle t}\)
\(\frac {\triangle [Br^{-}]}{\triangle t} = \frac {6}{5}\frac {\triangle [H^{+}]}{\triangle t}\)
\(\frac {\triangle [Br^{-}]}{\triangle t} = \frac {5}{6}\frac {\triangle [H^{+}]}{\triangle t}\)
\(\frac {\triangle [Br^{-}]}{\triangle t} = 6\frac {\triangle [H^{+}]}{\triangle t}\)
63.
In the presence of a catalyst, the heat evolved or absorbed during the reaction ............ .
increases
decreases
remains unchanged
may increase or decrease
64.
When ethyl acetate was hydrolysed in presence of 0.1 N HCI, the rate constant was found to be 5.40 \(\times\) 10-5 s-1 . From these values we can say that
H2SO4 is stronger than HCI
H2SO4 is weaker than HCI
Both the acids have equal strength
The data is insufficient to compare the strengths of HCI and H2SO4
65.
If the activatiopn energy for the forward reaction is 150 kJ mol-1 and that of the reserve reaction is 260 kJ mol-1, what is the enthalpy change for the reaction ?
410 kJ mol-1
-110 kJ mol-1
110 kJ mol-1
-410 kJ mol-1
66.
A chemical reaction was carried out at 300 K and 280 K the rate constants were found to be K1 and K2 respectively. Then
K2 = 4K1
K2 = 2K1
K2 = 0.25 K
K2 = 0.5 K1
67.
1[A] vs time is a straight line. The order of the reaction is
1
2
3
0
68.
75% of the first order reaction was completed in 32 min. 50% of the reaction was completed in
24 min
8 min
16 min
4 min
69.
For the reaction R \(\longrightarrow\) P, a graph of [R] against time is found to be a straight line with negative slope. What is the order of reaction ?
Second order
Third order
First order
Zero order
70.
Rate constant of a reaction (k) is 175 litre2 mol-2 sec-1. What is the order of reaction?
first
second
third
zero
71.
A first order reaction has a half-life period of 34.65 seconds. Its rate constant is
2 \(\times 10\) -2 sec-1
4 \(\times 10\) -4 sec-1
20 sec-1
2 \(\times 10\) -4 sec-1
72.
The unit of rate constant for a zero order reaction is
mol L-1 s-1
L mol-1 s-1
L2mol-1 s-1
s-1
73.
In a reaction \(\longrightarrow\) B, the rate of reaction increases two times on increasing the concentration of the reactant four times, then order of reaction is
0
2
1/2
4
74.
The rate of a gaseous reaction is given by the expression k [A][B]. If the volume of the reaction vessel is suddenly reduced to 1/4 th of the initial volume, the reaction rate relating to original rate will be
1/10
1/8
8
16
75.
For the reaction aA + bB \(\longrightarrow\) cC, if -3 \(\frac {d[A]}{dt} = +1.5 \frac {d[C]}{dt},\) then a, b, and c respectively are
3, 1, 2
2, 1, 3
1, 3, 2
6, 2, 3
1.
(c)
| Order with respect to A(g) | Order with respect to B(g) |
| Second | Zero |
2.
(b)
2.0
3.
(b)
166
4.
(a)
Activation energy of forward reaction is E1 + E2 and product is less stable than reactant.
5.
(a)
60 min
6.
(b)
2
7.
(a)
30
8.
(a)
zero
9.
(c)
24.1 s
10.
(b)
0.72 M
11.
(b)
0.5 x 10- 3 s-1
12.
(a)
13.
(d)
\(\log k-\left(\frac{E_{a}}{R T}\right)=A\)
14.
(b)
the ratio of rate constant differing by 10o preferably 25oC and 35oC
15.
(a)
\(\frac{2.303}{10}\) log 5 min-1
16.
(c)
\( \mathrm{H}_{2}+\mathrm{Cl}_{2} \longrightarrow 2 \mathrm{HCl}\\ \)
17.
(d)
zero
18.
(d)
one
19.
(b)
increases
20.
(d)
catalyst
21.
(a)
0.187 M min-1
22.
(b)
Hydrolysis of starch
23.
(c)
alters the reaction mechanism
24.
(c)
Heat of reaction is 6 kJ
25.
(a)
1 \(\times 10 ^{-4}\)
26.
(d)
1.0 \(\times 10^{6}s^{-1}\) and 38.3 kJ mol -1
27.
(d)
\(\frac {1000}{2.303}K\)
28.
(b)
increases
29.
(a)
less than \(\triangle H\)
30.
(a)
5 kJ mol-1
31.
(b)
921.2 R
32.
(d)
k1 = Ak2\({ e }^{ { Ea }/_{ 2 }RT }\)
33.
(a)
60.5 kJ mol-1
34.
(a)
t50 < tav < t75
35.
(b)
3
36.
(a)
\(\frac {dC}{dt} = k[A]\)
37.
(b)
4.0\(\times 10^{-4}M s^{-1}\)
38.
(d)
log k
39.
(c)
2
40.
(a)
10 times that required for half of the reaction
41.
(c)
3.47\(\times 10 ^ {-4} M/min\)
42.
(b)
0.29/K
43.
(c)
0
44.
(d)
first
45.
(c)
1
46.
(a)
0.0693
47.
(a)
40 mins
48.
(b)
2\(\times\) 0.693
49.
(a)
40 %
50.
(d)
\(\frac {2}{3}\)
51.
(a)
Low probability of simulateous collision of all the reacting species
52.
(b)
\(\frac { dC }{ dt } =\frac{1}{V}(\frac { dn }{ dt }) =\frac{1}{RT}(\frac { dP }{ dt }) \)
53.
Area under the curve must remain the same because sum of all fractions must be equal to i.e., total probability is one. Hence, (a) is incorrect. Also (d) is correct and (b),(c) are wrong.
54.
(a)
the fraction of molecules with most probable kinetic energy decreases at higher temperatures
55.
Activated complex has higher energy. When it decomposes. energy is always realeased and it may give products or reactants back.
56.
(b)
Order is less than the molecularity
57.
The value of rate constant of a pseudo first order reaction depends not only on temperaturebut also on concentration of reactant present in excess (See Solved Problem 2, page 4/42). Hence, (b) is correct
58.
(b)
It alters \(\triangle G\) of the reaction
59.
(b)
Rate = k[A] [B] 2
60.
Whole of the substance never reacts because in every half life, 50% of the substance reacts. Hence, time taken for 100% completion of a reaction is infinite.
61.
(a)
the same
62.
(c)
\(\frac {\triangle [Br^{-}]}{\triangle t} = \frac {5}{6}\frac {\triangle [H^{+}]}{\triangle t}\)
63.
(c)
remains unchanged
64.
(a) : For equimolar solution of twoi acids, \(\frac { Strength of Acid 1}{Strength of Acid 2} = \) \(\frac {k_1}{k_2}\)
65.
(b)
-110 kJ mol-1
66.
(c) : For every 10oC rise in temperature, rate constant is doubled, Hence, for 20oC rise in temperature, rate constant will become 4 times, i.e., K1 = 4 K2 or K2 = 0.25 K1
67.
(b) : log [A] vs times is linear for 1st order reactions, 1/[A] vs time is linear for 2nd order reactions ; 1/[A]2 vs time is linear for 3rd order reactions.
68.
(c) : 75% of reaction is completed in two half-lived i.e., 2 \(\times\) t 12 = 32 min or t 1/2 = 16 min
69.
(d) : For zero order reaction, k = \(\frac {1}{t}\)\(\left[ { \left[ A \right] }_{ 0 }-\left[ A \right] \right] \) or \( { \left[ A \right] }-\left[ A \right] _{ 0 } - kt\)
70.
(c) : On the basis of given units of k, the reactions of 3 rd order.
71.
(a) : \(k = \frac {0.693}{t/2}= \frac {0.693}{34.65}s^{-1} = 2 \times 10^{-2}\)s-1
72.
(a) Rate = \(\frac {dx}{dt} = k[A_o]^{o} = k \) or \(k = \frac {dx}{dt} = \frac {conc}{Time} =\frac {mol L^{-1}}{s}\)mol L-1 s-1.
73.
(c) : (i) r = k \(a ^ { \alpha}\) (ii) 2 r = k (4 a) \(\alpha\) dividing (ii) by (i), 4 \(\alpha\)= 2 or 2 \(\alpha\)= 1/2
74.
(d) : Rate = k ab. When volume is reduced to 1/4 th, Concentrations will become = 4 times
New rate = k (4 a) (4 b) = 16 k ab = 16 times.
75.
(c) : Dividing throught by 3, we get -\(\frac {d[A]}{dt}\) = \(-\frac {1}{3} \frac {d[B]}{dt}= + \frac {1}{2}\frac {d[C]}{dt}\)
This is so for the reaction A + 3B \(\longrightarrow\) 2 C
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