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Free download in PDF CBSE Class 12 Chemistry Short Questions & Answers. Here Gkseries provide Chemistry Solve Questions and Answers for CBSE Class 12 Students.
41
Which of the following statements about the catalyst is true?
[A]
A catalyst accelerates the rate of reaction by bringing down the activation energy.
[B]
A catalyst does not participate in reaction mechanism.
[C]
A catalyst makes the reaction feasible by making ∆G more negative.
[D]
A catalyst makes equilibrium constant more favourable for forward reaction.
Answer: A catalyst accelerates the rate of reaction by bringing down the activation energy.
42
Which among the following is a false statement?
[A]
For a first order reaction,
[B]
Molecularity of a reaction may be zero or fraction.
[C]
Rate of zero order reaction is independent of initial concentration of reactant.
[D]
Half life of a third order reaction is inversely proportional to square of initial concentration of the reactant.
Answer: Molecularity of a reaction may be zero or fraction.
43
What will be the fraction of molecules having energy equal to or greater than activation energy, Ea?
[A]
e-Ea/Rt
[B]
Ae-Ea/Rt
[C]
A
[D]
K
44
The half life of the first order reaction having rate constant K = 1.7 x 10-5s-1 is
[A]
11.3 h
[B]
1.8 h
[C]
12.1 h
[D]
9.7 h
45
For a chemical reaction A→B, it is found that the rate of reaction doubles when the concentration of A is increased four times. The order of reaction is
[A]
Zero
[B]
Half
[C]
Two
[D]
One
46
Activation energy of a chemical reaction can be determined by __________ .
[A]
determining the rate constant at standard temperature.
[B]
determining the rate constants at two temperatures.
[C]
determining probability of collision.
[D]
using catalyst.
Answer: determining the rate constants at two temperatures.
47
A first order reaction is 50% completed in 1.26 × 1014 s. How much time would it take for 100% completion?
[A]
infinite
[B]
1.26 × 1015 s
[C]
2.52 × 1014 s
[D]
2.52 × 1028 s
48
If cone, of reactant ‘A’ is increased 10 times and rate of reaction becomes 100 times. What is order with respect to ‘A’?
49
If the initial concentration of reactant is doubled, t1/2 is also doubled, the order of reaction is
[A]
zero
[B]
3
[C]
2
[D]
None of these
50
The rate of first order reaction is 0.04 mol L-1 s-1 at 10 sec. and 0.03 mol L-1 at 2C seconds after initiation of the reaction. t1/2 of reaction is
[A]
24.1 s
[B]
34.1 s
[C]
44.1 s
[D]
54.1 s
51
A first order reaction has specific reaction rate 10-2s-1. How much time it will take for 20g of reactant to reduce to 5g?
[A]
138.6 s
[B]
238.6 s
[C]
346.5 s
[D]
693.0 s
52
Which of the following is affected by catalyst?
[A]
∆H
[B]
∆S
[C]
∆G
[D]
Ea
53
The half life period of first order reaction is 1386 seconds. The specific rate constant of the reaction is
[A]
0.5 × 10-3 s-1
[B]
5.0 × 10-3 s-1
[C]
5.0 × 10-2 s-1
[D]
0.5 × 10-2 s-1
54
The rate constant of a reaction A → B is 0.6 × 103 mole per second. If the concentration of [A] is 5 M, then what will be concentration of [B] after 20 months?
[A]
0.72 M
[B]
3.60 M
[C]
1.08 M
[D]
0.36 M
55
The rate of first order reaction is 0.04 mol L-1 s-1 at 10 sec. and 0.03 mol L-1 at 2C seconds after initiation of the reaction. t1/2 of reaction is
[A]
24.1 s
[B]
34.1 s
[C]
44.1 s
[D]
54.1 s
56
Which of the following statements about the catalyst is true?
[A]
A catalyst accelerates the rate of reaction by bringing down the activation energy.
[B]
A catalyst makes equilibrium constant more favourable for forward reaction.
[C]
A catalyst does not participate in reaction mechanism.
[D]
A catalyst makes the reaction feasible by making ∆G more negative.
Answer: A catalyst accelerates the rate of reaction by bringing down the activation energy.
57
charcoal at same temperature and pressure is
[A]
CH4 < H2 < SO2
[B]
H2 < CH4 < SO2
[C]
H2 < SO2 < CH4
[D]
SO2 < CH4 < H2
58
The formation of micelles takes place only above
[A]
Kraft temperature
[B]
Critical temperature
[C]
Boyle’s temperature
[D]
Inversion temperature
Answer: Kraft temperature
59
Colloidion is 4% solution of which one of the following in alcohol-ether mixture.
[A]
Nitrocellulose
[B]
Glycol dinitrate
[C]
Cellulose acetate
[D]
Nitroglycerin
60
The protective power of lyophilic colloidal sol is expressed in terms of
[A]
gold number
[B]
oxidation numbers
[C]
CMC (Critical Micelle Concentration)
[D]
coagulation value
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