Undergraduate
Q. In a cyclic process, the net work done is equal to: (2020)
A.
Net heat added
B.
Change in internal energy
C.
Zero
D.
Net heat removed
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Solution
In a cyclic process, the net work done is equal to the net heat added to the system, as the internal energy returns to its initial state.
Correct Answer: A — Net heat added
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Q. In a damped harmonic oscillator, what happens to the amplitude over time? (2023)
A.
Increases
B.
Decreases
C.
Remains constant
D.
Oscillates
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Solution
In a damped harmonic oscillator, the amplitude decreases over time due to energy loss.
Correct Answer: B — Decreases
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Q. In a Daniell cell, which metal acts as the anode?
A.
Copper
B.
Zinc
C.
Silver
D.
Lead
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Solution
In a Daniell cell, Zinc acts as the anode.
Correct Answer: B — Zinc
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Q. In a first-order reaction, if the concentration of reactant decreases from 0.8 M to 0.2 M in 20 minutes, what is the rate constant? (2022)
A.
0.0347 min⁻¹
B.
0.0693 min⁻¹
C.
0.1 min⁻¹
D.
0.2 min⁻¹
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Solution
Using the first-order rate equation, k = (ln[A₀] - ln[A]) / t. Here, k = (ln(0.8) - ln(0.2)) / 20 = 0.0347 min⁻¹.
Correct Answer: A — 0.0347 min⁻¹
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Q. In a first-order reaction, if the rate constant k is 0.03 min⁻¹, what is the time required for the concentration to decrease to half? (2020)
A.
23.1 min
B.
10.0 min
C.
20.0 min
D.
15.0 min
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Solution
t₁/₂ = 0.693 / k = 0.693 / 0.03 = 23.1 min.
Correct Answer: A — 23.1 min
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Q. In a galvanic cell, if the anode reaction is 2Ag⁺ + 2e⁻ → 2Ag, what is the cathode reaction? (2022)
A.
Cu²⁺ + 2e⁻ → Cu
B.
Zn²⁺ + 2e⁻ → Zn
C.
Fe²⁺ + 2e⁻ → Fe
D.
Pb²⁺ + 2e⁻ → Pb
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Solution
The cathode reaction must be a reduction reaction, and Cu²⁺ + 2e⁻ → Cu is a common cathode reaction.
Correct Answer: A — Cu²⁺ + 2e⁻ → Cu
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Q. In a galvanic cell, if the anode reaction is 2H₂ → 4H⁺ + 4e⁻, what is the cathode reaction?
A.
O₂ + 4e⁻ + 4H⁺ → 2H₂O
B.
2H₂O + 4e⁻ → 2H₂ + O₂
C.
4H⁺ + 4e⁻ → 2H₂
D.
2H₂ + O₂ → 2H₂O
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Solution
The cathode reaction is O₂ + 4e⁻ + 4H⁺ → 2H₂O.
Correct Answer: A — O₂ + 4e⁻ + 4H⁺ → 2H₂O
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Q. In a galvanic cell, if the anode reaction is Ag⁺ + e⁻ → Ag, what is the cathode reaction?
A.
Cu²⁺ + 2e⁻ → Cu
B.
Zn²⁺ + 2e⁻ → Zn
C.
Fe²⁺ + 2e⁻ → Fe
D.
Pb²⁺ + 2e⁻ → Pb
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Solution
The cathode reaction must be a reduction; Ag⁺ + e⁻ → Ag is the anode reaction.
Correct Answer: A — Cu²⁺ + 2e⁻ → Cu
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Q. In a galvanic cell, if the anode reaction is Zn → Zn²⁺ + 2e⁻, what is the cathode reaction if the cathode is Cu²⁺ + 2e⁻ → Cu?
A.
Cu → Cu²⁺ + 2e⁻
B.
Zn²⁺ + 2e⁻ → Zn
C.
Zn + Cu²⁺ → Zn²⁺ + Cu
D.
Cu²⁺ + 2e⁻ → Cu
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Solution
The cathode reaction is Cu²⁺ + 2e⁻ → Cu.
Correct Answer: D — Cu²⁺ + 2e⁻ → Cu
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Q. In a group of 50 people, 20 are smokers. What is the probability of selecting a non-smoker? (2022)
A.
2/5
B.
3/5
C.
1/2
D.
1/4
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Solution
Number of non-smokers = 50 - 20 = 30. Probability = 30/50 = 3/5.
Correct Answer: B — 3/5
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Q. In a heat engine, if the input heat is 500 J and the work done is 300 J, what is the efficiency? (2023) 2023
A.
60%
B.
50%
C.
40%
D.
70%
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Solution
Efficiency (η) = Work done / Input heat = 300 J / 500 J = 0.6 or 60%.
Correct Answer: A — 60%
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Q. In a lottery, there are 10 tickets, and 2 are winning tickets. What is the probability of picking a winning ticket?
A.
1/5
B.
1/10
C.
1/2
D.
2/10
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Solution
Probability = Number of winning tickets / Total tickets = 2/10 = 1/5.
Correct Answer: A — 1/5
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Q. In a lottery, there are 10 tickets, and 3 are winning tickets. What is the probability of picking a winning ticket? (2022)
A.
1/3
B.
1/4
C.
1/5
D.
1/2
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Solution
Probability = Number of winning tickets / Total tickets = 3/10.
Correct Answer: A — 1/3
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Q. In a parallel circuit with two resistors of 6Ω and 3Ω, what is the total resistance? (2019)
A.
2Ω
B.
4Ω
C.
1.5Ω
D.
9Ω
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Solution
Using the formula 1/R_eq = 1/R1 + 1/R2, we get 1/R_eq = 1/6 + 1/3 = 1/6 + 2/6 = 3/6, thus R_eq = 2Ω.
Correct Answer: B — 4Ω
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Q. In a parallel RLC circuit, if R = 50 ohms, L = 0.2H, and C = 50μF, what is the total admittance? (2023)
A.
0.02 S
B.
0.04 S
C.
0.06 S
D.
0.08 S
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Solution
Y = 1/R + j(ωC - 1/ωL); calculate Y for given values.
Correct Answer: C — 0.06 S
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Q. In a parallel RLC circuit, if R = 50Ω, L = 0.2 H, and C = 50μF, what is the quality factor Q? (2015)
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Solution
Quality factor Q = (1/R) * √(L/C) = (1/50) * √(0.2/50e-6) = 2.
Correct Answer: B — 2
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Q. In a purely capacitive AC circuit, the current leads the voltage by how many degrees? (2022)
A.
0°
B.
90°
C.
180°
D.
270°
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Solution
In a purely capacitive circuit, the current leads the voltage by 90°.
Correct Answer: B — 90°
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Q. In a purely capacitive AC circuit, the current leads the voltage by how much phase angle? (2023)
A.
0 degrees
B.
90 degrees
C.
180 degrees
D.
270 degrees
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Solution
In a purely capacitive circuit, the current leads the voltage by 90 degrees.
Correct Answer: B — 90 degrees
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Q. In a reaction A → B, if the concentration of A decreases from 0.8 M to 0.4 M in 20 minutes, what is the average rate of reaction? (2019)
A.
0.02 M/min
B.
0.04 M/min
C.
0.1 M/min
D.
0.05 M/min
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Solution
Average rate = Δ[A]/Δt = (0.8 - 0.4) / 20 = 0.02 M/min.
Correct Answer: D — 0.05 M/min
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Q. In a reaction, if the concentration of reactant A is halved, and the rate constant remains the same, how does the rate change for a first-order reaction? (2021)
A.
Doubles
B.
Halves
C.
Remains the same
D.
Quadruples
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Solution
For a first-order reaction, if [A] is halved, the rate also halves.
Correct Answer: B — Halves
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Q. In a reaction, if the concentration of reactant A is halved, and the rate of reaction decreases to one-fourth, what is the order of the reaction? (2020)
A.
Zero
B.
First
C.
Second
D.
Third
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Solution
If the rate decreases to one-fourth when concentration is halved, the reaction is second-order.
Correct Answer: C — Second
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Q. In a reversible reaction, if the concentration of products increases, what happens to the equilibrium position? (2021) 2021
A.
It shifts to the left
B.
It shifts to the right
C.
It remains unchanged
D.
It shifts to the center
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Solution
According to Le Chatelier's principle, if the concentration of products increases, the equilibrium will shift to the left to counteract the change.
Correct Answer: A — It shifts to the left
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Q. In a reversible reaction, if the concentration of products increases, what happens to the equilibrium position? (2021)
A.
It shifts to the left
B.
It shifts to the right
C.
It remains unchanged
D.
It shifts to the center
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Solution
According to Le Chatelier's principle, if the concentration of products increases, the equilibrium will shift to the left to counteract the change.
Correct Answer: A — It shifts to the left
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Q. In a reversible reaction, if the concentration of reactants is increased, what will happen to the position of equilibrium? (2021)
A.
It will shift to the right
B.
It will shift to the left
C.
It will remain unchanged
D.
It will shift to the center
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Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium position to the right to favor the formation of products.
Correct Answer: A — It will shift to the right
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Q. In a second-order reaction, if the initial concentration is 0.1 M and the rate constant is 0.05 M⁻¹s⁻¹, what is the time taken to reach half the initial concentration? (2020)
A.
10 s
B.
20 s
C.
5 s
D.
15 s
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Solution
For a second-order reaction, t₁/₂ = 1 / (k[A₀]) = 1 / (0.05 * 0.1) = 200 s.
Correct Answer: B — 20 s
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Q. In a series RLC circuit, if R = 10 ohms, L = 0.1H, and C = 100μF, what is the resonant frequency? (2021)
A.
159.15 Hz
B.
100 Hz
C.
50 Hz
D.
200 Hz
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Solution
f0 = 1 / (2π√(LC)) = 1 / (2π√(0.1 × 100 × 10^-6)) = 159.15 Hz.
Correct Answer: A — 159.15 Hz
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Q. In a series RLC circuit, if R = 20Ω, L = 0.1 H, and C = 100μF, what is the resonant frequency? (2020)
A.
50 Hz
B.
100 Hz
C.
159.15 Hz
D.
200 Hz
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Solution
Resonant frequency f₀ = 1 / (2π√(LC)) = 1 / (2π√(0.1 * 100e-6)) = 159.15 Hz.
Correct Answer: C — 159.15 Hz
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Q. In a series RLC circuit, if the resistance is 10 ohms, inductance is 0.1 H, and capacitance is 100 μF, what is the resonant frequency? (2021)
A.
50 Hz
B.
100 Hz
C.
159 Hz
D.
200 Hz
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Solution
Resonant frequency f = 1/(2π√(LC)) = 1/(2π√(0.1 * 100e-6)) = 159.15 Hz.
Correct Answer: C — 159 Hz
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Q. In a zero-order reaction, the rate of reaction is independent of the concentration of the reactants. What is the unit of the rate constant (k) for a zero-order reaction? (2023)
A.
mol/L·s
B.
L^2/mol·s
C.
mol/L
D.
s^-1
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Solution
For a zero-order reaction, the rate is constant and does not depend on the concentration of reactants. The unit of the rate constant (k) is mol/L·s.
Correct Answer: A — mol/L·s
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Q. In a zero-order reaction, the rate of reaction is independent of which of the following? (2023) 2023
A.
Concentration of reactants
B.
Temperature
C.
Presence of a catalyst
D.
All of the above
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Solution
In a zero-order reaction, the rate is constant and does not depend on the concentration of the reactants.
Correct Answer: A — Concentration of reactants
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