# Sound – Old Year Questions

1. Put in ascending order of speed of sound in the mediums-

I . Water, II. Steel, III. Nitrogen :

(a) III, II, I
(b) III, I, II
(c) I, III, II
(d) II, I, III

[U.P.P.C.S. (Spl) (Mains) 2008]

2. The sound will have the highest velocity in-

(a) Vacuum
(b) Air
(c) Water
(d) Steel

[U.P. P.C.S. (Pre) 2018]

3. The velocity of sound in air is approximately-

(a) 10 km./sec.
(b) 10 mile/min.
(c) 343 m/sec.
(d) 3 × 1010/sec.

[42nd B.P.S.C. (Pre) 1997]

4. The velocity of sound is maximum in –

(a) Air
(b) Liquid
(c) Metal
(d) Vacuum

[U.P. Lower (Spl) (Pre) 2008, Uttarakhand P.C.S. (Pre) 2010]

5. If Va, Vw, and Vs respectively are the speed of sound in air, water, and steel, then-

(a) Va < Vw < Vs
(b) Vs < Vw < Va
(c) Vw < Vs < Va
(d) Vs < Va < Vw

[U.P. U.D.A./L.D.A. (Spl) (Mains) 2010]

6. In which medium the speed of sound is maximum at a temperature of around 20°C?

(a) Air
(b) Granite
(c) Water
(d) Iron

[Chhattisgarh P.C.S. (Pre) 2004]

7. Sound waves –

(a) Can travel in vacuum.
(b) Can travel only in solid.
(c) Can travel only in gases.
(d) Can travel both in solid and gaseous medium.

[U.P.P.C.S. (Pre) 2002]

8. Sound waves travel fastest in

(a) solids
(b) liquids
(c) gases
(d) vacuum

[M.P.P.C.S. (Pre) 2017]

9. In which of the following options sound may not be across/travel?

(a) Water
(b) vacuum
(c) Iron
(d) Air

[U.P.P.C.S. (Pre) 1990]

10. Sound waves do not travel in –

(a) Solids
(b) Liquids
(c) Gases
(d) Vacuum

[U.P.P.C.S. (Pre) 2014]

11. The walls of the hall, built for music concerts should –

(a) Amplify sound
(b) Transmit sound
(c) Refect sound
(d) Absorb sound

[U.P.P.C.S. (Mains) 2007]

12. To hear a clear echo, the minimum distance between the reflecting surface and the observer should be –

(a) 165 feet
(b) 165 metre
(c) 16.5 feet
(d) 16.5 meter

[U.P.P.C.S. (Mains) 2007]

13. How much should the minimum distance be between the source of sound and the reflecting surface, so that an echo can be heard clearly?

(a) 10 metre
(b) 17 metre
(c) 24 metre
(d) 30 metre

[R.A.S./R.T.S.(Pre) 2007]

14. One important characteristic of sound is ‘Pitch’, which depends upon

(a) Intensity
(b) Frequency
(c) Quality
(d) Amplitude

[U.P. P.C.S. (Mains) 2017]

15. Two astronauts cannot hear each other on the moon’s surface, because –

(a) Their ears have stopped working on the moon.
(b) No atmosphere on the moon.
(c) They wear special space suits on the moon.
(d) The sound travels much more slowly on the moon.

[U.P.U.D.A./L.D.A. (Pre) 2002]

16. An astronaut cannot hear his companion at the surface of the moon because –

(a) Produced frequencies are above the audio frequency.
(b) Temperature is too low during night and too high during day.
(c) There is no medium for sound propagation.
(d) There are many craters on the surface of the moon.

[U.P.P.C.S. (Mains) 2013]

17. Consider the following statements :

1. A future of a smaller length produces waves of lower frequency.
2. Sound travels in rocks in the form of longitudinal elastic waves only.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

[I.A.S. (Pre) 2007]

18. Consider the following statements about ultrasonic waves :

1. They can destroy insects.
2. They can clean clothes by removing dust.
3. They can be used to treat diseases.
4. They can control automatic doors.

Of the above statements

(a) 1 and 2 are correct
(b) 3 and 4 are correct
(c) 1, 2, and 3 are correct
(d) All are correct

[U.P.P.C.S. (Mains) 2004]

19. Ultrasonics are sound waves of frequency

(a) Greater than 20,000 Hz
(b) Less than 10,000 Hz
(c) Equal to 1000 Hz
(d) None of these

[U.P.P.C.S.(Pre) 2012]

20. What is the audible range (hearing range) of humans?

(a) 20 Hz – 20000 Hz
(b) 80 Hz – 100 Hz
(c) 2 lac Hz – 4 lac Hz
(d) 0 Hz – 20 Hz

[M.P. P.C.S. (Pre) 2018]

21. A biotechnique in which ultrasonic sound is used-

(a) Sonography
(b) E. C. G.
(c) E. E. G.
(d) X-ray

[R.A.S./R.T.S.(Pre) 2012]

22. Bats can fly during dark nights and also prey. This is because –

(a) The pupil of their eyes is large.
(b) Their night vision is very good.
(c) Every bird can do this.
(d) They produce ultrasonic waves and are guided by them.

[U.P.P.C.S. (Mains) 2005]

23. Consider the following statements :

1. The heart vibrates at infrasonic.
2. The speed of sound is more in gas than in liquid and solid.
3. Mach number is used to describe the speed of sound.
4. Ultrasonic sound has a frequency of more than 20,000 Hz.

Of these statements –

(a) 1, 2 and 3 are correct
(b) 2, 3 and 4 are correct
(c) 1, 3 and 4 are correct
(d) 1, 2 and 4 are correct

[U.P.P.C.S. (Mains) 2002]

24. In Stethoscope, the sound of the patient’s heartbeat reaches the doctor’s ears by :

(a) Multiple diffraction of sound
(b) Multiple reflections of sound
(c) Polarisation of sound
(d) Multiple refraction of sound

[R.A.S./ R.T.S. (Pre) 2021]

25. Which one of the following is the effect of the fight of a supersonic jet?

(a) Air pollution
(b) Eye disease
(c) Depletion in the ozone layer
(d) None of these

[M.P. P.C.S. (Pre) 1993]

26. Assertion (A): A jet aircraft moving at Mach number equal to 1 travels faster at an altitude of 15 km than while moving at Mach number equal to 1 near the sea level.
Reason (R): The velocity of sound depends on the temperature of the surrounding medium.

Codes :

(a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.

[I.A.S. (Pre) 2007]

27. Decibel is used to measure –

(a) Hemoglobin in blood
(b) Sugar in urine
(c) Sound in the atmosphere
(d) Particles in the air

[M.P.P.C.S. (Pre) 2005]

28. Consider the following statements:

1. A widely used musical scale called the diatonic scale has seven frequencies.
2. The frequency of the tone Sa is 256 Hz and that of Ni is 512 Hz.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

[I.A.S. (Pre) 2008]

29. A decibel unit is used to measure the –

(a) Speed of light
(b) Intensity of heat
(c) Intensity of sound

[Uttarakhand Lower Sub. (Pre) 2010]

30. What is the decibel level of sound produced by two persons in conversation?

[R.A.S./R.T.S.(Pre) 2003]

31. A noise level of 100 decibels would correspond to :

(a) Just audible sound
(b) Ordinary conversation
(c) Sound from a noisy street
(d) Noise from a machine shop

[I.A.S. (Pre) 2000]

32. Which of the following represents the decibel level of rustling of tree leaves in normal circumstances?

(a) 10 db
(b) 20 db
(c) 60 db
(d) 100 db

[U.P. P.C.S. (Pre) 2018]

33. As per the WHO, the safe noise level for a city is –

(a) 45 db
(b) 50 db
(c) 55 db
(d) 60 db

[U.P.P.C.S. (Mains) 2010]

34. The tolerable limit of noise for human being is around-

(a) 45 decibel
(b) 85 decibel
(c) 125 decibel
(d) 155 decibel

[R.A.S./R.T.S. (Pre) 1993]

35. Sound above what level (in decibels) is considered hazardous noise pollution?

(a) 30 db
(b) 100 db
(c) 80 db
(d) 120 db

[U.P.P.C.S.(Pre) 2013, U.P.P.C.S. (Mains) 2008]

36. Which one of the following units is used for the measurement of noise pollution?

(a) Nanometer
(b) Decibel
(c) Hertz
(d) None of the above

[U.P. P.C.S. (Mains) 2017]

37. The optimum sound level for human beings is-

(a) 90 db
(b) 60 db
(c) 120 db
(d) 100db

[R.A.S./R.T.S.(Pre) 2012]

38. Loudness of sound is measured in terms of the following :

(a) Frequency
(b) Amplitude
(c) Velocity
(d) Wavelength

[U.P. R.O./A.R.O. (Mains) 2017]

39. A worker was working on the rail track. A boy at a distance holds his ear near the rail track. This boy was able to hear the sound of the blow of a workman twice. It is because of :

(a) The speed of sound is greater in steel than in air.
(b) The speed of sound is greater in air than in steel.
(c) Part of the sound wave is reflected between the rail tracks.
(d) His ears are at different distance from the source.

[R.A.S./R.T.S. (Pre) 1994-95]

40. Which of the following statements is/are true in relation to sound waves?

Statement I: The speed of sound decreases when we go from a solid to a gaseous state
Statement II: In any medium as we decrease the temperature, the speed of sound increases
Statement III: The speed of sound is less in the aluminum medium than in glass medium

(a) Statement I, II and III all are true.
(b) Only Statement I and II are true.
(c) Only Statement I is true.
(d) Only Statement II and III are true.

[Chhattisgarh P.C.S. (Pre) 2020]

41. When a sound wave goes from one medium to another, the quantity that remains unchanged is :

(a) Frequency
(b) Amplitude
(c) Wavelength
(d) Speed
(e) None of the above/More than one of the above

[66th B.P.S.C. (Pre) (Re. Exam) 2020]

42. When the same tone is played on a sitar and a flute, the sound produced can be distinguished from each other because of the difference in :

(a) pitch, loudness, and quality
(b) pitch and loudness
(c) quality only
(d) loudness only

[I.A.S. (Pre) 1995]

43. The basic units of sound are called

(a) Morphemes
(b) Phonemes
(c) Semanteme
(d) Syntax

[U.P. P.C.S. (Mains) 2017]

44. Assertion (A): Reverberation mainly feels in large churches and in other large buildings.
Reason (R): The walls, roof, and ground may cause multiple sound reflections.

Code :
(a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.

[U.P. Lower Sub. (Spl) (Pre) 2003, U.P. Lower Sub. (Spl) (Pre) 2002]

45. A Decibel unit is used to measure –

(a) Light intensity
(b) Sound intensity
(c) Magnitude of Earthquake
(d) None of the above

[U.P.P.C.S. (Mains) 2011]

46. When T.V. is switched on :

(a) Audio and video both start simultaneously
(b) Audio is heard immediately but video starts later because video needs some warm up time
(c) Video starts immediately but audio is heard later because sound travels at a lesser speed than light
(d) It depends on the T.V. brand

[U.P.P.C.S. (Pre) 2007]

47. In television broadcasts, the picture signals are transmitted by –

(a) Amplitude modulation
(b) Frequency modulation
(c) Phase modulation
(d) Angle modulation

[R.A.S./R.T.S.(Pre) 2012]

48. The technique used to transmit audio signals in television broadcasts is –

(a) Amplitude modulation
(b) Pulse code modulation
(c) Frequency modulation
(d) Time dimension multiplication.

[U.P. U.D.A./L.D.A. (Spl) (Pre) 2010]