Q. For a reaction at standard conditions, if ΔG° is positive, what does it indicate?
A.
The reaction is spontaneous in the forward direction.
B.
The reaction is non-spontaneous in the forward direction.
C.
The reaction is at equilibrium.
D.
The reaction is spontaneous in the reverse direction.
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Solution
A positive ΔG° indicates that the reaction is non-spontaneous in the forward direction.
Correct Answer:
B
— The reaction is non-spontaneous in the forward direction.
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Q. For a reaction with a rate constant k, what is the relationship between the rate of reaction and the concentration of reactants for a first-order reaction?
A.
Rate = k[A]^2
B.
Rate = k[A]
C.
Rate = k[A]^3
D.
Rate = k[A]^0
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Solution
For a first-order reaction, the rate of reaction is directly proportional to the concentration of the reactant, given by Rate = k[A].
Correct Answer:
B
— Rate = k[A]
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Q. For a reaction with a rate constant of 0.02 M⁻¹s⁻¹ and initial concentration of 0.5 M, what is the time taken to reach 0.25 M in a second-order reaction? (2023)
A.
25 s
B.
50 s
C.
10 s
D.
20 s
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Solution
Using t = 1 / (k[A₀]) * (1/[A] - 1/[A₀]), t = 1 / (0.02 * 0.5) * (1/0.25 - 1/0.5) = 25 s.
Correct Answer:
A
— 25 s
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Q. For a reaction with an activation energy of 50 kJ/mol, what is the rate constant at 300 K if R = 8.314 J/(mol·K)? (2022)
A.
0.001 M/s
B.
0.01 M/s
C.
0.1 M/s
D.
1 M/s
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Solution
Using the Arrhenius equation, k = Ae^(-Ea/RT). Calculate k using the given values.
Correct Answer:
C
— 0.1 M/s
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Q. For a reaction with an activation energy of 50 kJ/mol, what will happen to the rate if the temperature is increased by 20°C? (2022)
A.
Rate decreases
B.
Rate remains the same
C.
Rate increases significantly
D.
Rate increases slightly
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Solution
Increasing the temperature generally increases the rate of reaction significantly due to higher kinetic energy.
Correct Answer:
C
— Rate increases significantly
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Q. For a reaction with ΔH = 100 kJ and ΔS = 200 J/K, at what temperature will the reaction become spontaneous?
A.
500 K
B.
250 K
C.
200 K
D.
100 K
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Solution
To find the temperature at which the reaction becomes spontaneous, set ΔG = 0: 0 = ΔH - TΔS. Thus, T = ΔH/ΔS = (100,000 J)/(200 J/K) = 500 K.
Correct Answer:
A
— 500 K
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Q. For a reaction with ΔH = 100 kJ/mol and ΔS = 200 J/mol·K, at what temperature will the reaction become spontaneous?
A.
500 K
B.
250 K
C.
200 K
D.
100 K
Show solution
Solution
To find the temperature at which the reaction becomes spontaneous, set ΔG = 0: 0 = ΔH - TΔS, thus T = ΔH/ΔS = 100,000 J / 200 J/K = 500 K.
Correct Answer:
A
— 500 K
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Q. For a reaction with ΔH = 50 kJ/mol and ΔS = 100 J/mol·K, at what temperature will the reaction become spontaneous?
A.
500 K
B.
250 K
C.
1000 K
D.
200 K
Show solution
Solution
To find the temperature at which the reaction becomes spontaneous, set ΔG = 0: 0 = ΔH - TΔS, thus T = ΔH/ΔS = (50,000 J/mol) / (100 J/mol·K) = 500 K.
Correct Answer:
A
— 500 K
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Q. For a rectangular plate of mass M and dimensions a x b, what is the moment of inertia about an axis through its center and parallel to side a?
A.
1/12 Mb^2
B.
1/3 Mb^2
C.
1/4 Mb^2
D.
1/6 Mb^2
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Solution
The moment of inertia of a rectangular plate about an axis through its center parallel to side a is I = 1/12 Mb^2.
Correct Answer:
A
— 1/12 Mb^2
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Q. For a reversible process, the change in entropy is given by which of the following?
A.
ΔS = Q/T
B.
ΔS = W/T
C.
ΔS = Q + W
D.
ΔS = 0
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Solution
For a reversible process, the change in entropy is given by ΔS = Q/T, where Q is the heat exchanged and T is the temperature.
Correct Answer:
A
— ΔS = Q/T
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Q. For a reversible process, the change in entropy of the system is equal to the heat absorbed divided by the temperature. This is expressed as:
A.
ΔS = Q/T
B.
ΔS = T/Q
C.
ΔS = Q + T
D.
ΔS = Q - T
Show solution
Solution
For a reversible process, the change in entropy (ΔS) is given by ΔS = Q/T, where Q is the heat absorbed and T is the temperature.
Correct Answer:
A
— ΔS = Q/T
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Q. For a reversible process, the change in entropy of the system is equal to the heat absorbed divided by the temperature. What is the formula?
A.
ΔS = Q/T
B.
ΔS = T/Q
C.
ΔS = Q*T
D.
ΔS = Q + T
Show solution
Solution
The change in entropy (ΔS) for a reversible process is given by ΔS = Q/T, where Q is the heat absorbed and T is the temperature.
Correct Answer:
A
— ΔS = Q/T
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Q. For a reversible process, the change in entropy of the universe is:
A.
Zero
B.
Positive
C.
Negative
D.
Undefined
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Solution
For a reversible process, the change in entropy of the universe is zero, as the system and surroundings are in equilibrium.
Correct Answer:
A
— Zero
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Q. For a reversible process, the efficiency of a Carnot engine is given by which formula?
A.
1 - (T2/T1)
B.
T1/T2
C.
T2/T1
D.
1 - (T1/T2)
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Solution
The efficiency of a Carnot engine is given by η = 1 - (T2/T1), where T1 is the temperature of the hot reservoir and T2 is the temperature of the cold reservoir.
Correct Answer:
A
— 1 - (T2/T1)
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Q. For a satellite in a circular orbit, which of the following is true about its kinetic and potential energy?
A.
K.E. = P.E.
B.
K.E. > P.E.
C.
K.E. < P.E.
D.
K.E. = 0
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Solution
For a satellite in a circular orbit, the kinetic energy is less than the potential energy, as K.E. = -1/2 P.E.
Correct Answer:
C
— K.E. < P.E.
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Q. For a satellite in a low Earth orbit, what is the approximate altitude range? (2000)
A.
200-2000 km
B.
500-10000 km
C.
1000-20000 km
D.
30000-40000 km
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Solution
Low Earth orbit satellites typically operate at altitudes ranging from about 200 km to 2000 km above the Earth's surface.
Correct Answer:
A
— 200-2000 km
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Q. For a satellite in a stable orbit, what must be true about the centripetal force and gravitational force?
A.
Centripetal force is greater than gravitational force
B.
Centripetal force is less than gravitational force
C.
Centripetal force equals gravitational force
D.
Centripetal force is independent of gravitational force
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Solution
For a satellite in a stable orbit, the centripetal force required for circular motion equals the gravitational force acting on the satellite.
Correct Answer:
C
— Centripetal force equals gravitational force
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Q. For a single slit of width 'a', what is the angular position of the first minimum?
A.
λ/a
B.
a/λ
C.
sin θ = λ/a
D.
tan θ = λ/a
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Solution
The angular position of the first minimum is given by sin θ = λ/a.
Correct Answer:
C
— sin θ = λ/a
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Q. For a solenoid of length L and n turns per unit length carrying current I, what is the magnetic field inside the solenoid?
A.
μ₀nI
B.
μ₀I/n
C.
μ₀I/L
D.
μ₀nI/L
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Solution
The magnetic field inside a solenoid is given by B = μ₀nI.
Correct Answer:
A
— μ₀nI
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Q. For a solenoid of length L, radius R, and carrying current I, what is the magnetic field inside the solenoid?
A.
μ₀nI
B.
μ₀I/L
C.
μ₀I/2L
D.
μ₀I/4L
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Solution
Using Ampere's Law, B = μ₀nI where n is the number of turns per unit length.
Correct Answer:
A
— μ₀nI
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Q. For a solid disk of mass M and radius R, what is the moment of inertia about an axis through its center and perpendicular to its plane?
A.
1/2 MR^2
B.
1/4 MR^2
C.
MR^2
D.
3/4 MR^2
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Solution
The moment of inertia of a solid disk about an axis through its center is I = 1/2 MR^2.
Correct Answer:
A
— 1/2 MR^2
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Q. For a solid disk of mass M and radius R, what is the moment of inertia about an axis perpendicular to the disk and passing through its center?
A.
1/2 MR^2
B.
1/4 MR^2
C.
MR^2
D.
3/4 MR^2
Show solution
Solution
The moment of inertia of a solid disk about an axis through its center is I = 1/2 MR^2.
Correct Answer:
A
— 1/2 MR^2
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Q. For a solution containing 2 components A and B, if the mole fraction of A is 0.6, what is the vapor pressure of the solution if the vapor pressure of pure A is 100 mmHg?
A.
60 mmHg
B.
100 mmHg
C.
40 mmHg
D.
80 mmHg
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Solution
According to Raoult's Law, the vapor pressure of the solution is P_A = X_A * P_A^0 = 0.6 * 100 mmHg = 60 mmHg.
Correct Answer:
D
— 80 mmHg
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Q. For a solution to obey Raoult's Law, the interactions between solute and solvent must be:
A.
Stronger than those in the pure components.
B.
Weaker than those in the pure components.
C.
Similar to those in the pure components.
D.
Non-existent.
Show solution
Solution
For a solution to obey Raoult's Law, the interactions between solute and solvent must be similar to those in the pure components.
Correct Answer:
C
— Similar to those in the pure components.
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Q. For a spherical Gaussian surface of radius R enclosing a charge Q, what is the electric field at a distance 2R from the center?
A.
Q/4πε₀(2R)²
B.
Q/4πε₀R²
C.
Q/4πε₀(2R)³
D.
0
Show solution
Solution
The electric field outside a spherical charge distribution behaves as if all the charge were concentrated at the center, so E = Q/4πε₀r².
Correct Answer:
A
— Q/4πε₀(2R)²
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Q. For a spontaneous process, the change in entropy of the universe must be:
A.
Zero
B.
Positive
C.
Negative
D.
Undefined
Show solution
Solution
For a spontaneous process, the total entropy change of the universe (system + surroundings) must be positive.
Correct Answer:
B
— Positive
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Q. For a spontaneous process, the change in Gibbs free energy (ΔG) is related to entropy (ΔS) how?
A.
ΔG = ΔH - TΔS
B.
ΔG = TΔS - ΔH
C.
ΔG = ΔS - ΔH
D.
ΔG = ΔH + TΔS
Show solution
Solution
The relationship is given by ΔG = ΔH - TΔS, where ΔG must be negative for a spontaneous process.
Correct Answer:
A
— ΔG = ΔH - TΔS
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Q. For a spontaneous process, the change in Gibbs free energy (ΔG) is related to entropy (ΔS) by which of the following equations?
A.
ΔG = ΔH + TΔS
B.
ΔG = ΔH - TΔS
C.
ΔG = TΔS - ΔH
D.
ΔG = ΔS - ΔH
Show solution
Solution
The correct relationship is ΔG = ΔH - TΔS, where ΔG must be negative for a spontaneous process.
Correct Answer:
B
— ΔG = ΔH - TΔS
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Q. For a spontaneous process, the change in Gibbs free energy (ΔG) is:
A.
Positive
B.
Negative
C.
Zero
D.
Undefined
Show solution
Solution
For a process to be spontaneous, the change in Gibbs free energy (ΔG) must be negative.
Correct Answer:
B
— Negative
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Q. For a system of particles, how is the moment of inertia calculated?
A.
Sum of individual moments
B.
Product of mass and distance squared
C.
Sum of mass times distance squared
D.
Average of all moments
Show solution
Solution
The moment of inertia for a system of particles is calculated as I = Σ(m_i * r_i^2), where m_i is the mass and r_i is the distance from the axis.
Correct Answer:
C
— Sum of mass times distance squared
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