Q. If the radius of curvature of a convex mirror is 20 cm, what is its focal length? (2022)
A.
10 cm
B.
20 cm
C.
30 cm
D.
40 cm
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Solution
The focal length (f) of a mirror is given by f = R/2. For a convex mirror, R is positive, so f = 20 cm / 2 = 10 cm.
Correct Answer: A — 10 cm
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Q. If the resistance of a conductor is doubled while the voltage remains constant, what happens to the current? (2020)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
According to Ohm's Law, if the resistance (R) is doubled and the voltage (V) remains constant, the current (I) will be halved (I = V/R).
Correct Answer: B — It halves
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Q. If the vapor pressure of pure solvent is 100 mmHg, and the vapor pressure of the solution is 80 mmHg, what is the mole fraction of the solute? (2022)
A.
0.2
B.
0.4
C.
0.5
D.
0.8
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Solution
Using Raoult's Law: P_solution = X_solvent * P_solvent. X_solvent = P_solution / P_solvent = 80/100 = 0.8, thus X_solute = 1 - X_solvent = 0.2.
Correct Answer: B — 0.4
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Q. If the vapor pressure of pure solvent is 100 mmHg, and the vapor pressure of the solution is 80 mmHg, what is the relative lowering of vapor pressure? (2022)
A.
0.2
B.
0.1
C.
0.5
D.
0.3
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Solution
Relative lowering of vapor pressure = (P° - P) / P° = (100 - 80) / 100 = 0.2.
Correct Answer: A — 0.2
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Q. If the voltage across a capacitor in an AC circuit is 100 V RMS, what is the peak voltage? (2022)
A.
100 V
B.
141.42 V
C.
200 V
D.
70.71 V
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Solution
The peak voltage (V_peak) is calculated as V_peak = V_rms × √2 = 100 V × √2 ≈ 141.42 V.
Correct Answer: B — 141.42 V
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Q. If the voltage across an inductor is 100 V and the current through it is 2 A, what is the inductive reactance? (2023)
A.
50 Ω
B.
200 Ω
C.
100 Ω
D.
25 Ω
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Solution
Inductive reactance (X_L) is given by X_L = V/I. Here, X_L = 100 V / 2 A = 50 Ω.
Correct Answer: A — 50 Ω
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Q. If two charges of +2 µC and -2 µC are placed 1 m apart, what is the net electric field at the midpoint? (2023)
A.
0 N/C
B.
4 N/C
C.
2 N/C
D.
8 N/C
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Solution
The electric fields due to both charges at the midpoint cancel each other out, resulting in a net electric field of 0 N/C.
Correct Answer: A — 0 N/C
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Q. If two resistors of 4Ω and 12Ω are connected in series, what is the total voltage across them if the current flowing is 2A? (2020)
A.
32V
B.
24V
C.
16V
D.
8V
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Solution
Total resistance R = 4Ω + 12Ω = 16Ω. Voltage V = I * R = 2A * 16Ω = 32V.
Correct Answer: B — 24V
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Q. If two resistors of 4Ω and 6Ω are connected in parallel, what is the equivalent resistance? (2022)
A.
2.4Ω
B.
10Ω
C.
24Ω
D.
1.5Ω
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Solution
Using the formula for parallel resistors, 1/R_eq = 1/R1 + 1/R2 = 1/4 + 1/6 = 5/12, R_eq = 12/5 = 2.4Ω.
Correct Answer: A — 2.4Ω
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Q. If two resistors of 5Ω and 10Ω are connected in series, what is the total resistance? (2021)
A.
5Ω
B.
10Ω
C.
15Ω
D.
20Ω
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Solution
In series, R_total = R1 + R2 = 5Ω + 10Ω = 15Ω.
Correct Answer: C — 15Ω
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Q. In a body-centered cubic (BCC) structure, how many atoms are there in one unit cell? (2022)
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Solution
In a body-centered cubic (BCC) structure, there are 2 atoms per unit cell (1 from the center and 1 from the corners).
Correct Answer: B — 2
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Q. In a chemical reaction, what does the term 'activation energy' refer to? (2023)
A.
Energy released during the reaction
B.
Energy required to initiate the reaction
C.
Energy needed to maintain the reaction
D.
Energy that is lost
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Solution
Activation energy is the minimum energy required to initiate a chemical reaction.
Correct Answer: B — Energy required to initiate the reaction
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Q. In a circuit with a 10Ω resistor and a 5V battery, what is the power consumed by the resistor? (2023)
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Solution
Power P = V^2/R = 5^2/10 = 25/10 = 2.5W.
Correct Answer: B — 2W
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Q. In a circuit with a 10Ω resistor and a 5Ω resistor in series, what is the total voltage across the circuit if the current is 2A? (2023)
A.
30V
B.
20V
C.
10V
D.
40V
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Solution
Total resistance R = 10Ω + 5Ω = 15Ω. Voltage V = I * R = 2A * 15Ω = 30V.
Correct Answer: B — 20V
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Q. In a circuit with a 12V battery and two 4Ω resistors in series, what is the current flowing through the circuit? (2023)
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Solution
Total resistance R = 4Ω + 4Ω = 8Ω. Current I = V/R = 12V/8Ω = 1.5A.
Correct Answer: B — 2A
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Q. In a circuit with a 15V battery and a 5Ω resistor, what is the voltage drop across the resistor? (2019)
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Solution
The voltage drop across the resistor is equal to the battery voltage, which is 15V.
Correct Answer: C — 15V
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Q. In a circuit with a 15V battery and two resistors of 5Ω and 10Ω in series, what is the voltage drop across the 10Ω resistor? (2022)
A.
5V
B.
10V
C.
15V
D.
0V
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Solution
The total resistance is 15Ω. The current I = V/R = 15V/15Ω = 1A. Voltage drop across 10Ω = I * R = 1A * 10Ω = 10V.
Correct Answer: B — 10V
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Q. In a circuit with a 24V battery and a 6Ω resistor, what is the power consumed by the resistor? (2020)
A.
48W
B.
72W
C.
96W
D.
144W
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Solution
Power (P) can be calculated using P = V^2 / R. Here, P = 24V^2 / 6Ω = 96W.
Correct Answer: B — 72W
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Q. In a circuit with a 24V battery and a total resistance of 8Ω, what is the power consumed by the circuit? (2023)
A.
72 W
B.
48 W
C.
36 W
D.
24 W
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Solution
Power P = V^2/R = 24^2/8 = 576/8 = 72 W.
Correct Answer: B — 48 W
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Q. In a circuit with a 9V battery and two resistors of 3Ω and 6Ω in series, what is the current flowing through the circuit? (2022)
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Solution
Total resistance R = 3Ω + 6Ω = 9Ω. Current I = V/R = 9V/9Ω = 1A.
Correct Answer: B — 2A
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Q. In a circuit with a voltage of 24V and a current of 6A, what is the resistance? (2020)
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Solution
Using Ohm's Law, R = V/I = 24V / 6A = 4Ω.
Correct Answer: D — 8Ω
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Q. In a circuit with an inductor, what happens to the current when the voltage is suddenly increased? (2020)
A.
Increases immediately
B.
Decreases immediately
C.
Increases gradually
D.
Decreases gradually
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Solution
In a circuit with an inductor, the current increases gradually due to the inductor's opposition to changes in current.
Correct Answer: C — Increases gradually
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Q. In a circuit, if the current is 5A and the resistance is 10Ω, what is the voltage? (2020)
A.
15V
B.
50V
C.
5V
D.
10V
Show solution
Solution
Using Ohm's Law, V = I * R = 5A * 10Ω = 50V.
Correct Answer: B — 50V
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Q. In a circuit, if the current is 5A and the resistance is 10Ω, what is the voltage across the resistor? (2021)
A.
15V
B.
50V
C.
5V
D.
10V
Show solution
Solution
Using Ohm's Law, V = I * R = 5A * 10Ω = 50V.
Correct Answer: B — 50V
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Q. In a circuit, if the resistance is doubled while the voltage remains constant, what happens to the current? (2021)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
Show solution
Solution
According to Ohm's law, I = V/R. If R is doubled, I will be halved.
Correct Answer: B — It halves
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Q. In a circuit, if the voltage is 24V and the current is 3A, what is the resistance? (2023)
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Solution
Using Ohm's Law, R = V / I = 24V / 3A = 8Ω.
Correct Answer: B — 6Ω
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Q. In a circuit, if the voltage is tripled and the resistance remains constant, what happens to the current? (2022)
A.
It triples
B.
It halves
C.
It remains the same
D.
It doubles
Show solution
Solution
According to Ohm's law, if V is tripled, I will also triple.
Correct Answer: A — It triples
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Q. In a closed system, if a reactant is removed from the equilibrium mixture, what will happen? (2019)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in temperature
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Solution
Removing a reactant will shift the equilibrium to the left to produce more reactants, according to Le Chatelier's principle.
Correct Answer: B — Shift to the left
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Q. In a closed system, if the internal energy increases, what can be said about the work done and heat added? (2020)
A.
Work done is positive and heat added is negative
B.
Work done is negative and heat added is positive
C.
Both work done and heat added are positive
D.
Both work done and heat added are negative
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Solution
According to the first law of thermodynamics, if the internal energy increases, it implies that either work is done on the system or heat is added to the system.
Correct Answer: C — Both work done and heat added are positive
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Q. In a closed system, if the internal energy increases, what can be said about the heat and work done? (2020)
A.
Heat is added and work is done on the system
B.
Heat is removed and work is done by the system
C.
Heat is added and work is done by the system
D.
No heat exchange occurs
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Solution
According to the first law of thermodynamics, if the internal energy increases, it implies that heat is added to the system and/or work is done on the system.
Correct Answer: A — Heat is added and work is done on the system
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