31. What is Specific Gravity of a liquid?
What is Specific Gravity of a liquid?
[A] ratio of the density of a liquid to the density of water
[B] product of the density of a substance to the density of water
[C] ratio of the density of water to the density of a liquid
[D] ratio of density of the liquid to the mass of the equal density of water
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Correct Answer: A [ ratio of the density of a liquid to the density of water ]
Notes:
Specific gravity of a liquid is the ratio of the density of a substance to the density of water. The density of liquid water at standard conditions on earth is approximately 1,000 kg/m3.
32.What is the density of water at 4°?
[A] 1.0
[B] 1.0 × 102 kg m–3
[C] 1.0 × 103 kg m–3
[D] 10 kg m–3
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Correct Answer: C [ 1.0 × 103 kg m–3 ]
Notes:
The density of water at 4°C (277 K) is 1.0 × 103 kg m–3. The relative density of a substance is the ratio of its density to the density of water at 4° C.
33.What happens to the viscosity of a liquid with increase in temperature?
[A] it increases
[B] it decreases
[C] it may increase or decrease
[D] No change
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Correct Answer: B [it decreases]
Notes:
The viscosity of liquids decreases with increase in temperature, while it increases in the case of gases.
34.What is the S.I unit of frequency?
[A] Second
[B] Watt
[C] Hertz
[D] Joule
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Correct Answer: C [Hertz]
Notes:
The frequency is defined as the number of periodic motions executed by body per second. The S.I unit of frequency is hertz (Hz).
35.What is the relationship between the time period and effective length of a simple pendulum?
[A] T ∝ l
[B] T = √l
[C] T ∝ √1/l
[D] T ∝ √l
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Correct Answer: D [ T ∝ √l]
Notes:
Time period T ∝ √l where l is the distance between point of suspension and center of mass of bob and is called effective length.
36.Which of the following is correct about mechanical waves?
[A] they require a medium to propagate
[B] they don’t require a medium to propagate
[C] may or may not require a medium to propagate
[D] None of the above
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Correct Answer: A [they require a medium to propagate]
Notes:
Mechanical waves require a medium for propagation as they cannot propagate through vacuum. Waves on a string, water waves, sound waves, seismic waves, etc. are the examples of mechanical waves.
37.Which of the following represents the speed of a sound wave?
[A] wavelength x frequency
[B] 2 x wavelength x frequency
[C] wavelength/frequency
[D] (wavelength x frequency)/2
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Correct Answer: A [wavelength x frequency]
Notes:
The speed of sound is defined as the distance which a point on a wave, such as a compression or a rarefaction, travels per unit time. It is represented by s = wavelength x frequency.
38.What do we call the temperature and pressure at which solid, liquid, and vapor phases of a particular substance coexist in equilibrium?
[A] Equilibrium point
[B] Triple point
[C] Normal point
[D] None of the above
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Correct Answer: B [Triple point]
Notes:
the triple point is the temperature and pressure at which solid, liquid, and vapor phases of a particular substance coexist in equilibrium.
39.Which of the following is the phenomenon responsible for the trade winds?
[A] Convection
[B] Conduction
[C] Radiation
[D] None of the above
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Correct Answer: A [Convection]
Notes:
The trade-wind, which is the steady surface wind on the earth blowing in from north-east towards the equator, is an example of natural convection.
40.Which of the following is true about an adiabatic wall?
[A] it allows flow of heat from one system to another
[B] it allows flow of particles from one system to another
[C] it does not allow flow of heat from one system to another
[D] None of the above
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Correct Answer: C [it does not allow flow of heat from one system to another]
Notes:
An adiabatic wall is an insulating wall (can be movable) that does not allow flow of energy (heat) from one to another.