Chapter 12 – Sound – MCQs
Chapter 12 – Sound – MCQs (Part 1: Q1–Q25)
Q1. Sound cannot travel through:
a) Solids
b) Liquids
c) Vacuum
d) Gases
Answer: c) Vacuum
👉 Explanation: Sound requires a medium (solid, liquid, or gas) for propagation. It cannot travel in a vacuum.
Q2. Which of the following is a longitudinal wave?
a) Light wave
b) Sound wave
c) Radio wave
d) X-rays
Answer: b) Sound wave
👉 Explanation: Sound waves are longitudinal in nature, where particles vibrate parallel to the direction of wave propagation.
Q3. The SI unit of frequency is:
a) Decibel
b) Hertz
c) Metre
d) Newton
Answer: b) Hertz
👉 Explanation: Frequency is measured in Hertz (Hz), which means cycles per second.
Q4. The time taken to complete one vibration is called:
a) Frequency
b) Amplitude
c) Time period
d) Wavelength
Answer: c) Time period
👉 Explanation: The time taken for one complete oscillation is the time period, which is the reciprocal of frequency.
Q5. What determines the pitch of a sound?
a) Amplitude
b) Frequency
c) Loudness
d) Speed
Answer: b) Frequency
👉 Explanation: Pitch depends on frequency – higher frequency produces higher pitch.
Q6. Which determines the loudness of sound?
a) Frequency
b) Amplitude
c) Wavelength
d) Pitch
Answer: b) Amplitude
👉 Explanation: Loudness depends on amplitude. Greater amplitude = louder sound.
Q7. The range of audible frequency for humans is:
a) 2–200 Hz
b) 20–20,000 Hz
c) 200–200,000 Hz
d) 2,000–20,000 Hz
Answer: b) 20–20,000 Hz
👉 Explanation: Humans can hear frequencies between 20 Hz and 20,000 Hz.
Q8. Ultrasonic waves have frequencies:
a) Below 20 Hz
b) 20–20,000 Hz
c) Above 20,000 Hz
d) Exactly 20 Hz
Answer: c) Above 20,000 Hz
👉 Explanation: Frequencies above 20,000 Hz are ultrasonic, beyond human hearing.
Q9. The speed of sound is maximum in:
a) Air
b) Water
c) Steel
d) Vacuum
Answer: c) Steel
👉 Explanation: Sound travels fastest in solids, followed by liquids, and slowest in gases.
Q10. The speed of sound in air at 25°C is approximately:
a) 150 m/s
b) 330 m/s
c) 500 m/s
d) 1200 m/s
Answer: b) 330 m/s
👉 Explanation: Speed of sound in air at room temperature (25°C) is about 330 m/s.
Q11. What type of wave needs a medium to travel?
a) Electromagnetic
b) Mechanical
c) Light
d) Radio
Answer: b) Mechanical
👉 Explanation: Mechanical waves (like sound) need a medium, while electromagnetic waves (light, radio) do not.
Q12. Which device is used to study sound waves graphically?
a) Microscope
b) Oscilloscope
c) Barometer
d) Thermometer
Answer: b) Oscilloscope
👉 Explanation: An oscilloscope displays sound waves, showing amplitude and frequency.
Q13. Which property of sound remains the same when it enters from one medium to another?
a) Speed
b) Frequency
c) Wavelength
d) Amplitude
Answer: b) Frequency
👉 Explanation: Frequency remains unchanged when sound passes from one medium to another.
Q14. In which medium is the speed of sound least?
a) Air
b) Water
c) Steel
d) Iron
Answer: a) Air
👉 Explanation: Sound travels slowest in gases, faster in liquids, and fastest in solids.
Q15. Sound is produced due to:
a) Resting objects
b) Vibrations of objects
c) Movement of light
d) Heat energy
Answer: b) Vibrations of objects
👉 Explanation: Vibrations of particles in a medium produce sound waves.
Q16. Which of the following is NOT a characteristic of sound?
a) Loudness
b) Pitch
c) Timbre
d) Mass
Answer: d) Mass
👉 Explanation: Mass is not a property of sound. Loudness, pitch, and timbre are.
Q17. The unit of loudness is:
a) Watt
b) Decibel
c) Hertz
d) Joule
Answer: b) Decibel
👉 Explanation: Loudness is measured in decibels (dB).
Q18. Which sound is called infrasonic?
a) Less than 20 Hz
b) 20–20,000 Hz
c) More than 20,000 Hz
d) None of these
Answer: a) Less than 20 Hz
👉 Explanation: Sounds below 20 Hz are infrasonic.
Q19. Which wave property determines shrillness of a sound?
a) Amplitude
b) Frequency
c) Speed
d) Loudness
Answer: b) Frequency
👉 Explanation: Higher frequency sounds are shrill, while lower frequency sounds are deep.
Q20. Sound waves are examples of:
a) Transverse mechanical waves
b) Longitudinal mechanical waves
c) Electromagnetic waves
d) Stationary waves only
Answer: b) Longitudinal mechanical waves
👉 Explanation: Sound waves are longitudinal and need a medium.
Q21. Which wave property changes when sound becomes louder?
a) Frequency
b) Wavelength
c) Amplitude
d) Speed
Answer: c) Amplitude
👉 Explanation: Loudness increases with amplitude.
Q22. Sound travels faster in:
a) Gases
b) Solids
c) Liquids
d) Vacuum
Answer: b) Solids
👉 Explanation: Due to closely packed particles, solids transmit sound fastest.
Q23. Which of the following animals can hear ultrasonic sounds?
a) Humans
b) Dogs
c) Whales
d) Both b and c
Answer: d) Both b and c
👉 Explanation: Dogs and whales can hear ultrasonic frequencies beyond human range.
Q24. Which property of sound helps to distinguish one person’s voice from another?
a) Loudness
b) Pitch
c) Timbre/Quality
d) Frequency
Answer: c) Timbre/Quality
👉 Explanation: Timbre or quality of sound differentiates voices even if loudness and pitch are similar.
Q25. The phenomenon of sound reflection is called:
a) Echo
b) Refraction
c) Diffraction
d) Dispersion
Answer: a) Echo
👉 Explanation: Echo is the reflection of sound heard again after bouncing from a surface.
Sound – MCQs (Part 2: Q26–Q50)
Q26. For an echo to be heard, the minimum distance between the source and the reflecting surface should be:
a) 10 m
b) 17 m
c) 34 m
d) 50 m
Answer: b) 17 m
👉 Explanation: The minimum distance must be 17 m so that the sound and echo are heard separately (time gap ≥ 0.1 s).
Q27. The speed of sound depends mainly on:
a) Frequency
b) Amplitude
c) Medium of propagation
d) Wavelength
Answer: c) Medium of propagation
👉 Explanation: Speed of sound depends on the nature and properties of the medium, not on frequency or amplitude.
Q28. Sound travels fastest in:
a) Steel
b) Water
c) Air
d) Wood
Answer: a) Steel
👉 Explanation: In solids like steel, particles are tightly packed, so sound travels fastest.
Q29. Which of the following can reflect sound waves?
a) Walls
b) Buildings
c) Mountains
d) All of these
Answer: d) All of these
👉 Explanation: Any large, hard surface can reflect sound and produce echoes.
Q30. The persistence of sound in a hall due to multiple reflections is called:
a) Echo
b) Reverberation
c) Resonance
d) Vibration
Answer: b) Reverberation
👉 Explanation: Reverberation occurs when reflected sounds overlap with the original, causing prolonged sound.
Q31. Which of the following helps to reduce reverberation in halls?
a) Carpets and curtains
b) Cushioned seats
c) Sound-absorbing materials on walls
d) All of these
Answer: d) All of these
👉 Explanation: Soft materials absorb sound and reduce reverberation.
Q32. The unit of sound intensity is:
a) Watt/m²
b) Decibel
c) Joule
d) Hertz
Answer: a) Watt/m²
👉 Explanation: Intensity of sound is defined as power per unit area and is measured in watt per square metre.
Q33. Which phenomenon is used in SONAR?
a) Refraction
b) Reflection
c) Diffraction
d) Absorption
Answer: b) Reflection
👉 Explanation: SONAR (Sound Navigation and Ranging) uses reflection of ultrasonic waves to detect objects underwater.
Q34. The full form of SONAR is:
a) Sound Navigation and Ranging
b) Sound Normalization and Response
c) Signal Navigation and Radar
d) Sound and Noise Adjustment Radar
Answer: a) Sound Navigation and Ranging
👉 Explanation: SONAR works on reflection of sound waves to measure depth and locate objects underwater.
Q35. Which waves are used in SONAR?
a) Infrasonic
b) Ultrasonic
c) Audible
d) Radio
Answer: b) Ultrasonic
👉 Explanation: SONAR uses ultrasonic waves as they travel long distances underwater and are not easily absorbed.
Q36. Which of the following is an application of ultrasound?
a) Medical imaging
b) Cleaning delicate objects
c) SONAR
d) All of these
Answer: d) All of these
👉 Explanation: Ultrasound is widely used in industry and medicine for imaging, cleaning, and SONAR.
Q37. Which property of sound wave is related to its intensity?
a) Amplitude²
b) Frequency
c) Time period
d) Wavelength
Answer: a) Amplitude²
👉 Explanation: Intensity of sound is directly proportional to the square of amplitude.
Q38. Which of the following can be heard by bats but not by humans?
a) Infrasonic waves
b) Audible sound
c) Ultrasonic waves
d) None
Answer: c) Ultrasonic waves
👉 Explanation: Bats use ultrasonic frequencies (>20,000 Hz) for echolocation.
Q39. The range of infrasonic sound is:
a) < 20 Hz
b) 20–20,000 Hz
c) > 20,000 Hz
d) None of these
Answer: a) < 20 Hz
👉 Explanation: Infrasonic sound has frequencies less than 20 Hz.
Q40. Sound waves are:
a) Transverse in nature
b) Longitudinal in nature
c) Electromagnetic waves
d) None of these
Answer: b) Longitudinal in nature
👉 Explanation: Sound waves are longitudinal; particles vibrate in the direction of wave propagation.
Q41. Which wave property does NOT change with medium?
a) Wavelength
b) Frequency
c) Speed
d) Amplitude
Answer: b) Frequency
👉 Explanation: Frequency of a wave is determined by the source and remains constant across media.
Q42. Which of these helps whales and dolphins to communicate underwater?
a) Visible light
b) Ultrasonic sound
c) Radio waves
d) Infrared
Answer: b) Ultrasonic sound
👉 Explanation: Whales and dolphins use ultrasonic sounds for communication and navigation underwater.
Q43. Which of the following is an example of resonance?
a) Swinging of a child when pushed at the right frequency
b) Echo
c) SONAR
d) Music in a hall
Answer: a) Swinging of a child when pushed at the right frequency
👉 Explanation: Resonance occurs when frequency of applied force matches the natural frequency.
Q44. The outer ear collects sound waves and sends them to:
a) Cochlea
b) Ear canal
c) Ear drum
d) Auditory nerve
Answer: c) Ear drum
👉 Explanation: The ear collects sound waves which strike the ear drum, causing it to vibrate.
Q45. Which part of the ear converts vibrations into electrical signals?
a) Ear drum
b) Ear canal
c) Cochlea
d) Pinna
Answer: c) Cochlea
👉 Explanation: The cochlea has sensory hair cells that convert vibrations into nerve impulses.
Q46. The loudness of sound is measured in:
a) Hertz
b) Decibels
c) Joules
d) Watts
Answer: b) Decibels
👉 Explanation: Loudness is measured on the decibel (dB) scale.
Q47. Which sound level can cause permanent damage to human ears?
a) 60 dB
b) 80 dB
c) 120 dB
d) 20 dB
Answer: c) 120 dB
👉 Explanation: Sounds above 120 dB can cause permanent hearing loss.
Q48. Which of the following best describes a wave motion?
a) Transfer of particles
b) Transfer of energy
c) Transfer of matter
d) None
Answer: b) Transfer of energy
👉 Explanation: In wave motion, energy is transferred but particles only vibrate around mean positions.
Q49. Which property of sound helps us to recognize different musical instruments?
a) Pitch
b) Timbre (quality)
c) Loudness
d) Frequency
Answer: b) Timbre (quality)
👉 Explanation: Timbre gives sound its unique quality, helping us identify instruments.
Q50. Which of the following is NOT an application of ultrasound?
a) Breaking kidney stones
b) Imaging of fetus
c) Studying atoms in crystals
d) Producing X-rays
Answer: d) Producing X-rays
👉 Explanation: Ultrasound cannot produce X-rays; it is used in medicine, industry, and research.
Sound – MCQs (Part 3: Q51–Q75)
Q51. Which of the following is NOT an example of sound reflection?
a) Echo in mountains
b) SONAR working
c) Reverberation in a hall
d) Refraction of light in water
Answer: d) Refraction of light in water
👉 Explanation: The first three are reflections of sound; refraction of light is unrelated.
Q52. Which factor does NOT affect the speed of sound in air?
a) Temperature
b) Humidity
c) Pressure
d) Medium type
Answer: c) Pressure
👉 Explanation: Speed of sound in air is independent of air pressure (as density and elasticity change proportionally).
Q53. Sound travels faster in humid air because:
a) Water vapour is lighter than dry air
b) Water vapour is heavier than oxygen
c) Humidity absorbs sound
d) None of these
Answer: a) Water vapour is lighter than dry air
👉 Explanation: Humid air is less dense, so sound travels faster in it.
Q54. Infrasonic sounds are used by which animals for communication?
a) Dogs
b) Elephants
c) Bats
d) Dolphins
Answer: b) Elephants
👉 Explanation: Elephants produce and detect infrasonic sounds (<20 Hz) to communicate over long distances.
Q55. Ultrasonic waves are used for:
a) Detecting cracks in metals
b) Cleaning delicate objects
c) Medical imaging
d) All of these
Answer: d) All of these
👉 Explanation: Ultrasonics are widely used in industry, medicine, and cleaning due to their high frequency.
Q56. The human ear can hear sounds in the range of:
a) 20–200 Hz
b) 20–20,000 Hz
c) 200–200,000 Hz
d) Above 20,000 Hz
Answer: b) 20–20,000 Hz
👉 Explanation: This is the audible range of frequencies for human beings.
Q57. Which wave property corresponds to the “shrillness” of a sound?
a) Amplitude
b) Frequency
c) Speed
d) Loudness
Answer: b) Frequency
👉 Explanation: Higher frequency → more shrill sound; lower frequency → deep sound.
Q58. Which of the following cannot hear ultrasonic sounds?
a) Dogs
b) Bats
c) Humans
d) Dolphins
Answer: c) Humans
👉 Explanation: Humans are limited to 20–20,000 Hz, but dogs, bats, dolphins detect ultrasonic waves.
Q59. In SONAR, the depth of the sea is measured by:
a) Speed of ship
b) Time taken by echo
c) Loudness of sound
d) Frequency of sound
Answer: b) Time taken by echo
👉 Explanation: Depth = (speed of sound × time taken) ÷ 2.
Q60. If the speed of sound in water is 1500 m/s, and the echo returns in 2 s, the depth of sea is:
a) 750 m
b) 1500 m
c) 3000 m
d) 6000 m
Answer: b) 1500 m
👉 Explanation: Depth = (1500 × 2) ÷ 2 = 1500 m.
Q61. The loudness of sound depends on:
a) Amplitude
b) Frequency
c) Pitch
d) Speed
Answer: a) Amplitude
👉 Explanation: Greater amplitude → louder sound.
Q62. The SI unit of sound level is:
a) Watt
b) Hertz
c) Decibel
d) Joule
Answer: c) Decibel
👉 Explanation: Sound intensity level is measured in decibels (dB).
Q63. Which of the following is a transverse wave?
a) Sound in air
b) Light
c) Longitudinal wave in steel
d) None
Answer: b) Light
👉 Explanation: Light is an electromagnetic transverse wave. Sound is always longitudinal.
Q64. The quality or timbre of sound is distinguished by its:
a) Waveform
b) Amplitude
c) Frequency
d) Speed
Answer: a) Waveform
👉 Explanation: Waveform defines timbre, which helps distinguish different instruments/voices.
Q65. Noise pollution can cause:
a) Hearing impairment
b) Lack of sleep
c) Hypertension
d) All of these
Answer: d) All of these
👉 Explanation: Noise pollution affects both health and environment.
Q66. The phenomenon of multiple reflections of sound is used in:
a) Megaphones
b) Trumpets
c) Stethoscopes
d) All of these
Answer: d) All of these
👉 Explanation: Devices like megaphones, trumpets, and stethoscopes use multiple reflections.
Q67. Which one is the correct relation?
a) Speed = Frequency × Amplitude
b) Speed = Wavelength ÷ Frequency
c) Speed = Frequency × Wavelength
d) Speed = Amplitude ÷ Frequency
Answer: c) Speed = Frequency × Wavelength
👉 Explanation: v = f × λ is the wave equation for sound.
Q68. In which part of the ear are vibrations converted into electrical signals?
a) Pinna
b) Cochlea
c) Ear drum
d) Ear canal
Answer: b) Cochlea
👉 Explanation: Cochlea converts vibrations into nerve impulses sent to the brain.
Q69. Which part of the ear vibrates when sound enters?
a) Cochlea
b) Ear canal
c) Ear drum
d) Auditory nerve
Answer: c) Ear drum
👉 Explanation: Ear drum (tympanum) vibrates when struck by sound waves.
Q70. Which sound has the highest frequency?
a) Bass drum
b) Human whistle
c) Male voice
d) Female voice
Answer: b) Human whistle
👉 Explanation: Whistles produce high-frequency sounds, often near the upper limit of human hearing.
Q71. Which of these can produce ultrasonic sound?
a) Dog
b) Bat
c) Cat
d) Human
Answer: b) Bat
👉 Explanation: Bats emit ultrasonic waves for navigation (echolocation).
Q72. Which of these is NOT a use of ultrasound?
a) Locating cracks in metals
b) Measuring depth of oceans
c) Cleaning jewelleries
d) Producing electricity
Answer: d) Producing electricity
👉 Explanation: Ultrasound is not used for electricity generation.
Q73. A doctor uses a stethoscope because:
a) It produces sound
b) It reduces reverberation
c) It works on multiple reflection of sound
d) It magnifies objects
Answer: c) It works on multiple reflection of sound
👉 Explanation: Stethoscopes amplify heartbeat by multiple reflections of sound.
Q74. The frequency of a wave is the reciprocal of:
a) Amplitude
b) Speed
c) Time period
d) Wavelength
Answer: c) Time period
👉 Explanation: Frequency = 1 ÷ Time period (f = 1/T).
Q75. Which property of sound helps in identifying a friend’s voice on phone?
a) Loudness
b) Pitch
c) Quality (Timbre)
d) Frequency
Answer: c) Quality (Timbre)
👉 Explanation: Timbre (quality) of voice is unique and helps distinguish individuals.
Sound – MCQs (Part 4: Q76–Q100)
Q76. Sound waves are best described as:
a) Electromagnetic and longitudinal
b) Mechanical and longitudinal
c) Mechanical and transverse
d) Electromagnetic and transverse
Answer: b) Mechanical and longitudinal
👉 Explanation: Sound is a mechanical wave requiring a medium, and particles vibrate parallel to wave direction.
Q77. The pitch of sound depends on:
a) Amplitude
b) Frequency
c) Wavelength
d) Loudness
Answer: b) Frequency
👉 Explanation: Higher frequency produces higher pitch, and lower frequency produces deeper sounds.
Q78. The loudness of sound depends on:
a) Frequency
b) Amplitude
c) Wavelength
d) Time period
Answer: b) Amplitude
👉 Explanation: Loudness increases with amplitude of the sound wave.
Q79. Which of these animals uses echolocation to navigate?
a) Lion
b) Dog
c) Bat
d) Cat
Answer: c) Bat
👉 Explanation: Bats use ultrasonic echolocation to find food and navigate in the dark.
Q80. Which physical quantity is common between sound and light waves?
a) Speed in vacuum
b) Frequency
c) Medium requirement
d) Nature of propagation
Answer: b) Frequency
👉 Explanation: Both light and sound waves are characterized by frequency, though their nature differs.
Q81. Which of these sounds has the lowest frequency?
a) Thunder
b) Whistle
c) Flute
d) Human voice
Answer: a) Thunder
👉 Explanation: Thunder produces deep low-frequency sounds, often infrasonic.
Q82. Which device works on the principle of sound reflection?
a) Periscope
b) Stethoscope
c) Microscope
d) Telescope
Answer: b) Stethoscope
👉 Explanation: A stethoscope uses multiple reflections of sound to amplify the heartbeat.
Q83. A tuning fork produces:
a) Transverse waves in air
b) Longitudinal waves in air
c) Stationary waves in solids only
d) Electromagnetic waves
Answer: b) Longitudinal waves in air
👉 Explanation: Vibrations of tuning fork prongs produce longitudinal sound waves in air.
Q84. Which frequency range is used in medical ultrasonography?
a) 20–200 Hz
b) 200–20,000 Hz
c) 1–15 MHz
d) Above 1 GHz
Answer: c) 1–15 MHz
👉 Explanation: Medical imaging uses ultrasound frequencies in the MHz range.
Q85. What happens to wavelength of sound when it enters water from air?
a) Increases
b) Decreases
c) Remains same
d) Becomes zero
Answer: a) Increases
👉 Explanation: Speed of sound increases in water; since frequency is constant, wavelength increases (λ = v/f).
Q86. Which is NOT true about ultrasonic waves?
a) They are inaudible to humans
b) They can clean delicate objects
c) They can pass through vacuum
d) They are used in SONAR
Answer: c) They can pass through vacuum
👉 Explanation: Ultrasonics are mechanical waves; they need a medium.
Q87. Which characteristic of sound helps us distinguish between notes of flute and violin?
a) Frequency
b) Loudness
c) Timbre
d) Amplitude
Answer: c) Timbre
👉 Explanation: Timbre or quality of sound differentiates instruments.
Q88. If time period of a wave is 0.01 s, its frequency is:
a) 1 Hz
b) 10 Hz
c) 100 Hz
d) 1000 Hz
Answer: c) 100 Hz
👉 Explanation: f = 1/T = 1/0.01 = 100 Hz.
Q89. The product of frequency and wavelength of a wave gives:
a) Amplitude
b) Speed
c) Loudness
d) Time period
Answer: b) Speed
👉 Explanation: Wave equation: v = f × λ.
Q90. What is the speed of sound in vacuum?
a) 0 m/s
b) 330 m/s
c) 1500 m/s
d) Infinite
Answer: a) 0 m/s
👉 Explanation: Sound requires a medium; in vacuum, its speed is zero.
Q91. The unit of pitch is the same as:
a) Hertz
b) Decibel
c) Watt
d) Joule
Answer: a) Hertz
👉 Explanation: Pitch depends on frequency, measured in Hertz.
Q92. A sound wave has frequency 200 Hz and speed 340 m/s. Its wavelength is:
a) 1.2 m
b) 1.7 m
c) 2.5 m
d) 3.4 m
Answer: b) 1.7 m
👉 Explanation: λ = v/f = 340/200 = 1.7 m.
Q93. Which phenomenon makes megaphones and trumpets work?
a) Reflection of sound
b) Refraction of sound
c) Resonance
d) Diffraction
Answer: a) Reflection of sound
👉 Explanation: These devices use reflection to direct sound energy in one direction.
Q94. The minimum sound level heard by a normal human ear is:
a) 0 dB
b) 10 dB
c) 20 dB
d) 30 dB
Answer: a) 0 dB
👉 Explanation: 0 dB is the threshold of hearing for an average healthy human ear.
Q95. Which part of the ear sends electrical signals to the brain?
a) Cochlea
b) Ear drum
c) Pinna
d) Ear canal
Answer: a) Cochlea
👉 Explanation: Cochlea converts vibrations into nerve signals transmitted to the brain.
Q96. If the amplitude of sound doubles, its intensity becomes:
a) Two times
b) Three times
c) Four times
d) Eight times
Answer: c) Four times
👉 Explanation: Intensity ∝ (Amplitude)². Doubling amplitude → intensity × 4.
Q97. Which frequency is inaudible to humans?
a) 15 Hz
b) 150 Hz
c) 1500 Hz
d) 15,000 Hz
Answer: a) 15 Hz
👉 Explanation: Below 20 Hz is infrasonic, inaudible to humans.
Q98. Which device is used to locate submarines underwater?
a) Telescope
b) Microscope
c) SONAR
d) Periscope
Answer: c) SONAR
👉 Explanation: SONAR uses reflection of ultrasonic waves underwater.
Q99. Which of the following waves can travel in vacuum?
a) Sound waves
b) Ultrasonic waves
c) Infrasonic waves
d) Light waves
Answer: d) Light waves
👉 Explanation: Sound needs a medium, but light (electromagnetic) can travel in vacuum.
Q100. The sound of thunder is heard after the lightning is seen because:
a) Sound travels faster than light
b) Light travels faster than sound
c) Sound and light have same speed
d) Light gets absorbed in clouds
Answer: b) Light travels faster than sound
👉 Explanation: Light speed (3 × 10⁸ m/s) is much faster than sound speed (≈ 330 m/s in air).
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❓ Short FAQ Section (4–5 Questions)
Q1. What type of wave is sound?
Sound is a mechanical longitudinal wave that requires a medium (solid, liquid, or gas) to travel.
Q2. What is the audible range of sound for humans?
Humans can hear sounds in the range of 20 Hz to 20,000 Hz.
Q3. Why are MCQs on the chapter “Sound” important for Class 9 students?
They help in revising key concepts, strengthen exam preparation, and are commonly asked in CBSE Class 9 exams.
Q4. Which properties determine loudness and pitch of sound?
Loudness depends on amplitude, while pitch depends on frequency of the sound wave.
Q5. What are the key applications of ultrasound studied in Class 9?
Ultrasound is used in SONAR, medical imaging, cleaning delicate objects, and detecting cracks in machinery.
