Undergraduate
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 measurement, if the uncertainty is ±0.5 cm, what is the range of the measurement 10.0 cm? (2023)
A.
9.5 cm to 10.5 cm
B.
9.0 cm to 11.0 cm
C.
10.0 cm to 10.5 cm
D.
10.0 cm to 11.0 cm
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Solution
The range is calculated as (10.0 - 0.5) cm to (10.0 + 0.5) cm, which is 9.5 cm to 10.5 cm.
Correct Answer: A — 9.5 cm to 10.5 cm
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Q. In a p-n junction, what happens when the junction is forward biased? (2019)
A.
Depletion region widens
B.
Depletion region narrows
C.
No current flows
D.
Reverse current increases
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Solution
When a p-n junction is forward biased, the depletion region narrows, allowing current to flow.
Correct Answer: B — Depletion region narrows
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Q. In a parallel circuit with two resistors of 6Ω and 3Ω, what is the total current if a 12V battery is connected? (2021)
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Solution
First, find the equivalent resistance: 1/R_eq = 1/6 + 1/3 = 1/2, so R_eq = 2Ω. Then, I = V/R_eq = 12V / 2Ω = 6A.
Correct Answer: C — 6A
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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 PN junction diode, what happens when it is forward biased? (2019)
A.
Depletion region widens
B.
Depletion region narrows
C.
No current flows
D.
Reverse current increases
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Solution
When a PN junction diode is forward biased, the depletion region narrows, allowing current to flow.
Correct Answer: B — Depletion region narrows
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Q. In a PN junction, what is formed at the junction of p-type and n-type materials? (2021)
A.
Electric field
B.
Magnetic field
C.
Thermal field
D.
Gravitational field
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Solution
An electric field is formed at the junction of p-type and n-type materials due to the diffusion of charge carriers.
Correct Answer: A — Electric field
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Q. In a predator-prey relationship, what is the primary effect of an increase in the prey population? (2021)
A.
Decrease in predator population
B.
Increase in predator population
C.
Decrease in prey population
D.
No effect on predator population
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Solution
An increase in the prey population typically leads to an increase in the predator population due to more available food.
Correct Answer: B — Increase in predator population
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Q. In a predator-prey relationship, which of the following is true? (2022)
A.
Predators are always larger than their prey.
B.
Prey populations are always larger than predator populations.
C.
Predators help control prey populations.
D.
Prey can never escape predators.
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Solution
Predators help control the population of prey species, maintaining a balance in the ecosystem.
Correct Answer: C — Predators help control prey populations.
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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 at equilibrium, if the concentration of a reactant is increased, what will happen to the equilibrium position? (2019)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on temperature
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Solution
Increasing the concentration of a reactant will shift the equilibrium position to the right, favoring the formation of products.
Correct Answer: A — Shift to the right
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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 redox reaction, which of the following statements is true? (2020)
A.
Oxidation involves gain of electrons
B.
Reduction involves loss of electrons
C.
Oxidation state of an element decreases during oxidation
D.
Reduction involves gain of electrons
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Solution
Reduction is defined as the gain of electrons, which decreases the oxidation state of the element.
Correct Answer: D — Reduction involves gain of electrons
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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 products increases, what happens to the rate of the forward reaction? (2021)
A.
It increases
B.
It decreases
C.
It remains constant
D.
It becomes zero
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Solution
According to Le Chatelier's principle, if the concentration of products increases, the system will shift to the left, decreasing the rate of the forward reaction.
Correct Answer: B — It decreases
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Q. In a reversible reaction, if the concentration of reactants is increased, what will happen to the equilibrium position? (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, if the concentration of reactants is increased, the equilibrium will shift 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 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 reversible reaction, if the forward reaction is exothermic, what can be said about the reverse reaction? (2022)
A.
It is also exothermic
B.
It is endothermic
C.
It has no effect on equilibrium
D.
It is spontaneous
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Solution
If the forward reaction is exothermic, the reverse reaction must be endothermic, as it absorbs heat.
Correct Answer: B — It is endothermic
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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 circuit with a 9V battery and three resistors of 1Ω, 2Ω, and 3Ω, what is the total resistance? (2019)
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Solution
Total resistance in series is R_total = R1 + R2 + R3 = 1 + 2 + 3 = 6Ω.
Correct Answer: A — 6Ω
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Q. In a series RLC circuit, at resonance, the impedance is equal to which of the following? (2020)
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Solution
At resonance in a series RLC circuit, the impedance (Z) is equal to the resistance (R) because the inductive and capacitive reactances cancel each other out.
Correct Answer: B — R
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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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