Q. In a diffraction pattern, the central maximum is observed to be the brightest. What is the reason for this? (2022)
A.
It has the least path difference
B.
It has the maximum path difference
C.
It has the maximum intensity
D.
It has the minimum intensity
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Solution
The central maximum has the maximum intensity because all light waves arrive in phase at this point, leading to constructive interference.
Correct Answer:
C
— It has the maximum intensity
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Q. In a double-slit experiment, if the distance between the slits is 0.1 mm and the screen is 1 m away, what is the fringe separation for light of wavelength 500 nm? (2020)
A.
0.5 mm
B.
0.1 mm
C.
0.2 mm
D.
0.3 mm
Show solution
Solution
Fringe separation (β) = λD/d = (500 x 10^-9 m)(1 m)/(0.1 x 10^-3 m) = 0.5 mm.
Correct Answer:
A
— 0.5 mm
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Q. In a double-slit experiment, if the wavelength of light is halved, what happens to the fringe width? (2020)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
Show solution
Solution
Fringe width (β) is given by β = λD/d. If λ is halved, β will also be halved.
Correct Answer:
A
— It doubles
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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
Show solution
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 half-life is constant, what can be said about the rate constant? (2023)
A.
It increases with time
B.
It decreases with time
C.
It remains constant
D.
It is zero
Show solution
Solution
In a first-order reaction, the half-life is constant, which indicates that the rate constant remains constant.
Correct Answer:
C
— It remains constant
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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
Show solution
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
Show solution
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
Show solution
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
Show solution
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
Show solution
Solution
The cathode reaction is Cu²⁺ + 2e⁻ → Cu.
Correct Answer:
D
— Cu²⁺ + 2e⁻ → Cu
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Q. In a game, the probability of winning is 0.2. What is the probability of losing? (2019)
A.
0.2
B.
0.5
C.
0.8
D.
0.3
Show solution
Solution
The probability of losing is 1 - 0.2 = 0.8.
Correct Answer:
C
— 0.8
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Q. In a generator, mechanical energy is converted into electrical energy through: (2019)
A.
Electromagnetic induction
B.
Thermal conduction
C.
Chemical reaction
D.
Nuclear fission
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Solution
In a generator, mechanical energy is converted into electrical energy through the process of electromagnetic induction.
Correct Answer:
A
— Electromagnetic induction
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Q. In a generator, mechanical energy is converted into which type of energy? (2021)
A.
Thermal energy
B.
Chemical energy
C.
Electrical energy
D.
Nuclear energy
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Solution
In a generator, mechanical energy is converted into electrical energy through the process of electromagnetic induction.
Correct Answer:
C
— Electrical energy
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Q. In a generator, what is the role of the rotating coil? (2022)
A.
To create a magnetic field
B.
To change the direction of current
C.
To induce EMF by changing magnetic flux
D.
To store electrical energy
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Solution
In a generator, the rotating coil induces EMF by changing the magnetic flux through it.
Correct Answer:
C
— To induce EMF by changing magnetic flux
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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
Show solution
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 group of 50 people, 20 are smokers. What is the probability that a randomly selected person is a non-smoker? (2021)
A.
1/2
B.
3/5
C.
2/5
D.
1/5
Show solution
Solution
There are 50 - 20 = 30 non-smokers. The probability is 30/50 = 3/5.
Correct Answer:
B
— 3/5
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Q. In a harmonic oscillator, if the mass is doubled while keeping the spring constant the same, how does the frequency change? (2021)
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
Show solution
Solution
Frequency (f) = (1/2π)√(k/m). If mass (m) is doubled, frequency decreases.
Correct Answer:
B
— Decreases
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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%
Show solution
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
Show solution
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
Show solution
Solution
Probability = Number of winning tickets / Total tickets = 3/10.
Correct Answer:
A
— 1/3
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Q. In a lottery, there are 100 tickets and 10 winning tickets. What is the probability of picking a winning ticket? (2023)
A.
1/10
B.
1/5
C.
1/20
D.
1/50
Show solution
Solution
Probability of winning = 10/100 = 1/10.
Correct Answer:
A
— 1/10
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Q. In a magnetic field, the force on a charged particle is maximum when the angle between the velocity and the magnetic field is: (2019)
A.
0 degrees
B.
90 degrees
C.
180 degrees
D.
45 degrees
Show solution
Solution
The force on a charged particle in a magnetic field is maximum when the angle between the velocity and the magnetic field is 90 degrees.
Correct Answer:
B
— 90 degrees
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Q. In a nuclear reaction, if a nucleus emits an alpha particle, what happens to its atomic number? (2023)
A.
It increases by 2
B.
It decreases by 2
C.
It remains the same
D.
It decreases by 4
Show solution
Solution
An alpha particle consists of 2 protons and 2 neutrons, so the atomic number decreases by 2.
Correct Answer:
B
— It decreases by 2
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Q. In a parallel circuit with two resistors of 4Ω and 12Ω, what is the total current if the voltage across the circuit is 24V? (2022)
Show solution
Solution
First, find the equivalent resistance: 1/R_eq = 1/4 + 1/12 = 3/12 + 1/12 = 4/12, R_eq = 3Ω. Then, I = V/R_eq = 24V / 3Ω = 8A.
Correct Answer:
C
— 8A
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Q. In a parallel circuit with two resistors of 4Ω and 12Ω, what is the total current if the voltage across them is 24V? (2022)
Show solution
Solution
Total current I = V/R_eq. First, find R_eq = 1/(1/4 + 1/12) = 3Ω. Then, I = 24V / 3Ω = 8A.
Correct Answer:
A
— 6A
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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)
Show solution
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
Show solution
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 circuit with two resistors of 8Ω and 4Ω, what is the total current if the voltage across the circuit is 16V? (2022)
Show solution
Solution
First, find the equivalent resistance: 1/R_eq = 1/8 + 1/4 = 1/8 + 2/8 = 3/8, so R_eq = 8/3Ω. Then, I = V/R_eq = 16V / (8/3)Ω = 16 * 3/8 = 6A.
Correct Answer:
D
— 8A
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Q. In a parallel circuit, if one branch has a resistance of 4Ω and another has 8Ω, what is the equivalent resistance? (2020)
A.
2.67Ω
B.
3Ω
C.
4Ω
D.
6Ω
Show solution
Solution
1/R_eq = 1/4 + 1/8 = 2/8 + 1/8 = 3/8, so R_eq = 8/3Ω ≈ 2.67Ω.
Correct Answer:
A
— 2.67Ω
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Q. In a parallel plate capacitor, if the distance between the plates is increased, what happens to the capacitance? (2022)
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
Show solution
Solution
The capacitance (C) of a parallel plate capacitor is inversely proportional to the distance (d) between the plates. If d increases, C decreases.
Correct Answer:
B
— It decreases
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