Major Competitive Exams
Q. In a closed system, if the temperature of an ideal gas is doubled while the volume remains constant, what happens to the pressure?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
According to Gay-Lussac's law, pressure is directly proportional to temperature at constant volume. Therefore, if the temperature doubles, the pressure also doubles.
Correct Answer: A — It doubles
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Q. In a closed system, if the volume is decreased, what will happen to the equilibrium of the reaction 2A(g) + B(g) ⇌ 3C(g)?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Depends on temperature
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Solution
Decreasing the volume increases the pressure, and the equilibrium will shift towards the side with fewer moles of gas, which is the left side.
Correct Answer: A — Shift to the left
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Q. In a closed system, if the volume of gas is halved at constant temperature, what happens to the pressure?
A.
Halved
B.
Doubled
C.
Remains the same
D.
Increases four times
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Solution
According to Boyle's law, if the volume is halved, the pressure is doubled.
Correct Answer: B — Doubled
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Q. In a closed system, if the volume of the gas is doubled at constant temperature, what happens to the pressure?
A.
Doubles
B.
Halves
C.
Remains constant
D.
Increases four times
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Solution
According to Boyle's Law, at constant temperature, if the volume of a gas is doubled, the pressure is halved.
Correct Answer: B — Halves
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Q. In a communication system, if the signal-to-noise ratio (SNR) is 20 dB, what is the linear SNR?
A.
10
B.
20
C.
100
D.
200
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Solution
Linear SNR = 10^(SNR(dB)/10) = 10^(20/10) = 100.
Correct Answer: C — 100
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Q. In a communication system, what does 'multiplexing' refer to?
A.
Combining multiple signals into one
B.
Separating signals
C.
Amplifying signals
D.
Encoding signals
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Solution
Multiplexing refers to combining multiple signals into one for transmission.
Correct Answer: A — Combining multiple signals into one
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Q. In a communication system, what does 'noise' refer to?
A.
The desired signal
B.
Unwanted disturbances that affect the signal
C.
The modulation technique used
D.
The bandwidth of the channel
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Solution
Noise refers to unwanted disturbances that interfere with the desired signal, affecting the quality of communication.
Correct Answer: B — Unwanted disturbances that affect the signal
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Q. In a communication system, what does 'signal-to-noise ratio' (SNR) measure?
A.
The strength of the signal relative to background noise
B.
The total power of the signal
C.
The bandwidth of the communication channel
D.
The efficiency of the modulation technique
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Solution
Signal-to-noise ratio (SNR) measures the strength of the signal relative to the background noise, indicating the quality of the communication.
Correct Answer: A — The strength of the signal relative to background noise
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Q. In a compound microscope, which lens is the eyepiece?
A.
Convex lens
B.
Concave lens
C.
Bifocal lens
D.
Plano-convex lens
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Solution
The eyepiece of a compound microscope is a convex lens.
Correct Answer: A — Convex lens
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Q. In a compound microscope, which lens is the objective lens?
A.
The lens closest to the eye
B.
The lens closest to the object
C.
The lens with the longer focal length
D.
The lens with the shorter focal length
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Solution
The objective lens is the one closest to the object being viewed.
Correct Answer: B — The lens closest to the object
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Q. In a concave lens, the focal length is: (2023)
A.
Positive
B.
Negative
C.
Zero
D.
Infinite
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Solution
The focal length of a concave lens is negative, indicating that it diverges light rays.
Correct Answer: B — Negative
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Q. In a concentration cell, if the concentration of one half-cell is 0.1 M and the other is 1 M, what is the cell potential?
A.
0.059 V
B.
0.118 V
C.
0.0591 V
D.
0.1181 V
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Solution
Using the Nernst equation, E = (0.0591/n) log([C1/C2]), where n=1.
Correct Answer: B — 0.118 V
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Q. In a concentration cell, the potential difference arises due to:
A.
Different temperatures
B.
Different concentrations
C.
Different pressures
D.
Different materials
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Solution
In a concentration cell, the potential difference arises due to different concentrations of the same species.
Correct Answer: B — Different concentrations
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Q. In a conical pendulum, if the angle of the string with the vertical is increased, what happens to the horizontal component of the tension?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
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Solution
As the angle increases, the horizontal component of tension increases to provide the necessary centripetal force.
Correct Answer: A — Increases
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Q. In a cross between a homozygous tall plant (TT) and a homozygous short plant (tt), what will be the genotype of the F1 generation? (2019)
A.
TT
B.
tt
C.
Tt
D.
TtTt
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Solution
The genotype of the F1 generation from a cross between TT and tt will be Tt (all offspring will be heterozygous).
Correct Answer: C — Tt
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Q. In a cyclic process, the change in internal energy is:
A.
Positive
B.
Negative
C.
Zero
D.
Depends on the path taken
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Solution
In a cyclic process, the system returns to its initial state, so the change in internal energy is zero.
Correct Answer: C — Zero
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Q. In a cyclic process, the change in internal energy of the system is:
A.
Positive
B.
Negative
C.
Zero
D.
Depends on the work done
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Solution
In a cyclic process, the system returns to its initial state, so the change in internal energy is zero.
Correct Answer: C — Zero
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Q. In a cyclic process, the net work done by the system is equal to:
A.
The net heat added to the system
B.
The change in internal energy
C.
The heat lost by the system
D.
Zero
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Solution
In a cyclic process, the net work done by the system is zero because the system returns to its initial state.
Correct Answer: D — Zero
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Q. In a cyclic process, the net work done is equal to the:
A.
Change in internal energy
B.
Heat added to the system
C.
Heat removed from the system
D.
Net heat transfer
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Solution
In a cyclic process, the net work done is equal to the heat added to the system.
Correct Answer: B — Heat added to the system
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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 cyclic process, what is the net change in internal energy of the system?
A.
Positive
B.
Negative
C.
Zero
D.
Depends on the path taken
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Solution
In a cyclic process, the system returns to its initial state, so the net change in internal energy is zero.
Correct Answer: C — Zero
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Q. In a cyclic process, what is the net change in internal energy?
A.
Positive
B.
Negative
C.
Zero
D.
Depends on the process
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Solution
In a cyclic process, the system returns to its initial state, so the net change in internal energy is zero.
Correct Answer: C — Zero
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Q. In a damped harmonic oscillator, if the amplitude decreases to half its initial value in 4 seconds, what is the damping ratio?
A.
0.25
B.
0.5
C.
0.75
D.
1.0
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Solution
The damping ratio can be calculated using the logarithmic decrement method, leading to ζ = 0.25.
Correct Answer: A — 0.25
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Q. In a damped harmonic oscillator, if the damping coefficient is increased, what happens to the amplitude of oscillation?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
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Solution
In a damped harmonic oscillator, increasing the damping coefficient results in a decrease in the amplitude of oscillation over time.
Correct Answer: B — Decreases
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Q. In a damped harmonic oscillator, if the damping coefficient is increased, what happens to the time period of oscillation?
A.
Time period increases
B.
Time period decreases
C.
Time period remains the same
D.
Time period becomes zero
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Solution
The time period of a damped harmonic oscillator remains the same; damping affects amplitude, not period.
Correct Answer: C — Time period remains the same
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Q. In a damped harmonic oscillator, if the mass is doubled while keeping the damping coefficient constant, what happens to the damping ratio?
A.
Doubles
B.
Halves
C.
Remains the same
D.
Increases by a factor of √2
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Solution
Damping ratio (ζ) = c / (2√(mk)). If m is doubled, ζ is halved.
Correct Answer: B — Halves
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Q. In a damped harmonic oscillator, what effect does increasing the damping coefficient have on the oscillation?
A.
Increases amplitude
B.
Decreases amplitude
C.
Increases frequency
D.
Decreases frequency
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Solution
Increasing the damping coefficient results in a decrease in amplitude over time, leading to quicker energy loss.
Correct Answer: B — Decreases amplitude
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Q. In a damped harmonic oscillator, what happens to the amplitude of oscillation over time?
A.
Increases
B.
Decreases
C.
Remains constant
D.
Oscillates
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Solution
In a damped harmonic oscillator, the amplitude of oscillation decreases over time due to energy loss.
Correct Answer: B — Decreases
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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 damped harmonic oscillator, which factor primarily determines the rate of energy loss?
A.
Mass of the oscillator
B.
Spring constant
C.
Damping coefficient
D.
Frequency of oscillation
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Solution
The damping coefficient determines how quickly the energy is lost in a damped harmonic oscillator.
Correct Answer: C — Damping coefficient
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