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The answer is (B) below 20 Hz

Dogs can hear sounds upto about 65,000 Hz. That’s why dogs can receive ultrasonic sound signals produced by the vibration of the earth and start barking in advance before the actual earthquake is felt.

Thunder is heard few seconds later after the flash because speed of light in atmosphere for air is 3 × 10⁸ ms^-2 which is very high, as compared to the speed of sound which is only 330 ms^-1. So sound of thunder reaches us later than the flash.

The speed of sound (344 m/s) is less than the speed of light (3 x 10⁸ m/s). Sound of thunder takes more time to reach the Earth as compared to light. Hence, a flash is seen before we hear a thunder.

The amount of sound energy passing each second through unit area is called the intensity of sound.

The sound is heard before because the sound waves travel through the air molecules by creating vibrations while the smell reaches to us through the movement of the air molecules.

Correct option is A) total silence

Practicing these Class 8 Science MCQ Questions of Sound with Answers will help you to answer every question that is being asked in the exams. Class 8 Science MCQ Questions of sound with Answers is available here. CBSE MCQ Questions for Class 8 Science Sound assist the students to understand the concepts thoroughly and to score good marks.

We prepared these MCQ Questions on the basis latest exam Pattern and syllabus. Students can solve NCERT Class 8 Science objective types Questions before the exam to know their preparation level. At Sarthaks eConnect, you can get MCQ Questions for Class 8 Science of all Chapters with detailed Answers. Have a look at the below listed 2o Multiple Choice Question of Sound Chapter.

Practice Class 8 Science MCQ Questions chapter-wise

1. The voice box is also called as

(a) stomach
(b) heart
(c) larynx
(d) mouth

2. Sound is a kind of

(a) work
(b) energy
(c) force
(d) pressure

3. The hearing range of the human ear is

(a) 20 Hz to 20,000 Hz
(b) less than 20 Hz
(c) more than 20,000 Hz
(d) 20 Hz to 25,000 Hz

4. Pitch of sound is determined by its

(a) frequency
(b) speed
(c) amplitude
(d) loudness

5. The frequency of subsonic sound is

(a) more than 20 Hz
(b) 100 Hz
(c) less than 20 Hz
(d) more than 20,000 Hz

6. Cochlea is a part of

(a) hearing organ
(b) sound-producing organ
(c) muscular organ
(d) air pollution

7. 1 hertz is equal to

(a) 1 vibration per minute
(b) 10 vibrations per minute
(c) 60 vibrations per minute
(d) 600 vibrations per minute

8. Sound cannot travel through

(a) air
(b) water
(c) air
(d) vacuum

9. The sound in the audible range is called

(a) ultrasonic sound
(b) sonic sound
(c) subonic sound
(d) light sound

10. A pendulum oscillates 20 times in 4 seconds. Find its time period.

(a) 0.05 sec
(b) 0.001 sec
(c) 0.2 sec
(d) 0.1 sec

11. Loudness of sound is determined by

(a) pitch
(b) frequency
(c) amplitude
(d) time period

12. The number of vibrations made by a vibrating body in one second is

(a) frequency
(b) noise
(c) loudness
(d) pitch

13. Sound is produced by

(a) Non-Vibrating objects only
(b) Vibrating and non-vibrating objects
(c) Vibration has no relation to sound
(d) Vibrating objects only

14. Vibration is also known as

(a) Vibratory motion
(b) Translatory motion
(c) Oscillatory motion
(d)  None of these

15. Frequency is expressed in

(a) Kilometer
(b) Hertz
(c) gram
(d) Degree centigrade

16. Loudness becomes painful above how many decibels?

(a) 60 dB
(b) 250 dB
(c) 80 dB
(d) 20,000 dB

17. When the amplitude of vibration is large, the sound produced is

(a)  No sound
(b) feeble
(c) loud
(d) No relation between amplitude and sound

18. Voice of a man is heavy compared to a woman because

(a) Female vocal cord is longer
(b) Male vocal cord is shorter
(c) Male vocal cord is longer
(d) The concept is not related

19. The loudness of a sound depends on:

(a) its amplitude
(b) its frequency
(c) its time period
(d) its speed

20. An object is vibrating at 50 hertz. What is its time period?

(a) 0.02 s
(b) 2 s
(c) 0.2 s
(d) 20.0 s

21. Sound can travel through:

(a) gases only
(b) solids only
(c) liquids only
(d) solids, liquids, and gases

22. A shehnai produces sound from:

(a) vibrating strings
(b) vibrating membrane
(c) vibrating air column
(d) none of these

23. When the amplitude is small, the sound produced is:

(a) loud
(b) Moderate
(c) Faint
(d) Shrill

24. Which of the following is not caused due to noise pollution?

(a) lack of sleep
(b) hypertension
(c) Diabetes
(d) Anxiety

25. High frequency of sound vibrations will produce a:

(a) loud sound
(b) shrill
(c) meak sound
(d) low piched sound

Answer:

1. Answer: (c) larynx

Explanation: The larynx, or voice box, is located in the neck and performs several important functions in the body.

2. Answer: (b) energy

Explanation: Sound energy is defined as the movement of vibrations through matter. Sound energy is produced when an object vibrates, which results in noise. 

3. Answer: (a) 20 Hz to 20,000 Hz

Explanation: While 20 to 20,000Hz forms the absolute borders of the human hearing range, our hearing is most sensitive in the 2000 - 5000 Hz frequency range.

4. Answer: (a) frequency

Explanation: The number of vibrations per second or frequency determines the pitch of a sound. Frequency is directly proportional to pitch. Higher the frequency, the higher the pitch.

5. Answer: (c) less than 20 Hz

Explanation: The range of frequency of subsonic vibration is less than 20 Hz. They cannot be perceived by the human ear. They are also referred to as infrasonic vibrations.

6. Answer: (a) hearing organ

Explanation: The cochlea, the hearing organ, is located inside the inner ear. The snail-like cochlea is made up of three fluid-filled chambers that spiral around a bony core, which contains a central channel called the cochlear duct. Inside the cochlear duct is the main hearing organ, the spiral-shaped organ of the Corti.

7. Answer: (c) 60 vibrations per minute

Explanation: Frequency is the rate at which the current changes its direction per second. One hertz is equal to one cycle per second and therefore 1 hertz is equal to 60 vibrations per minute.

8. Answer: (d) vacuum

Explanation: Sound can not travel through a vacuum. All the other options are given in the question, air, water, and iron sound can travel through them. Sound needs a medium to travel and all the other option like air, water, and iron provide a medium to the sound to travel through them.

9. Answer: (b) sonic sound

Explanation: The audio frequency is called audible frequency. Frequency is expressed in SI unit hertz (Hz). Sound below this audible range is called sub-sonic and the sound above this range is called ultrasonic.

10. Answer: (c) 0.2 sec

Explanation: Time period of pendulum = 0.2 seconds. Hence, the time period of the pendulum as per the given information is 0.2 seconds.

11. Answer: (c) amplitude

Explanation: Thus, the loudness of a sound depends on the amplitude which determines its loudness and volume. ∴ The loudness of the sound depends on its Amplitude. 

12. Answer: (a) frequency

Explanation: The number of vibrations exhibited by a vibrating particle in one second is called its frequency.

13. Answer: (d) Vibrating objects only

Explanation: Sound is produced by Vibrating objects only.

14. Answer: (c) Oscillatory motion

Explanation: A type of motion in which a particle vibrates about a fixed point is called vibratory motion. A type of motion in which a particle moves to and fro about a fixed point is called oscillatory motion.

15. Answer: (b) Hertz

Explanation: Frequency is expressed in Hertz.

16. Answer: (c) 80 dB

Explanation: When the loudness of a sound exceeds 80 dB, it becomes painful and intolerable.

17. Answer: (c) loud

Explanation: The large amplitude of sound vibrations will produce a loud sound. The intensity of sound is identified by loudness. The loudness of sound is proportional to the square of the amplitude of the vibration producing the sound. If the amplitude of vibration is large, the sound produced is loud.

18. Answer: (c) Male vocal cord is longer

Explanation: The voice of a man is heavy compared to a woman because the hormone testosterone elongates the vocal cord.

19. Answer: (a) its amplitude

Explanation: Loudness is directly proportional to the amplitude of sound waves. If the amplitude is high then the sound will be louder and the sound will be feeble if the amplitude is low.

20. Answer: (a) 0.02 s

Explanation: If an object is vibrating at 50 hertz

50 = 1/T

T = 1/50

T = 0.02s

Its time period will be 0.02 sec

21. Answer: (d) solids, liquids, and gases

Explanation: This movement is called vibration. Sound travels more quickly through solids than through liquids and gases because the molecules of a solid are closer together. Hence, sounds can travel in solids, liquids, and gases.

22. Answer: (c) vibrating air column

Explanation: A shehnai produces sound from a vibrating air column. A drum produces sound from a vibrating stretched membrane. The frequency of oscillations is the number of oscillations per second.

23. Answer: (c) Faint

Explanation: Amplitude is the magnitude of the sound produced. Therefore, if the magnitude of amplitude is small then the sound produced is faint, or if the amplitude is high then the sound produced is loud.

24. Answer: (c) Diabetes

Explanation: Diabetes is not caused by noise pollution, as diabetes is caused due to lack of insulin in the human body.

25. Answer: (b) shrill

Explanation: A high-pitched sound is called a shrill sound while a low-pitched sound is called a deep sound. Therefore, an object vibrating with high frequency produces a high-frequency sound wave, that is, it produces a shrill or high pitched sound.

Click here Practice MCQ Questions for Sound Class 8

CBSE Class 9 Science MCQ Questions of Sound with answers accessible here. The MCQ Questions for Class 9 have been set up according to the most recent syllabus and exam pattern proposed by CBSE. Students can solve Class 9 Science Sound Multiple Choice Questions with Answers to realize their preparation level.

MCQ Questions of Sound for class 9 science and whenever practiced appropriately can assist you with getting the higher marks class. Refer more MCQ Questions for class 9 Science and furthermore download more most up-to-date examination notes for all subjects.

Practice MCQ Questions for class 9 Chapter-Wise

1. Infrasound can be heard by

(a) dog
(b) bat
(c) rhinoceros
(d) human beings

2. In SONAR, we use

(a) ultrasonic waves
(b) infrasonic waves
(c) radio waves
(d) audible sound waves

3. When we change feeble sound too loud sound we increase its

(a) frequency
(b) amplitude
(c) velocity
(d) wavelength

4. Earthquake produces which kind of sound before the main shock wave begins

(a) ultrasound
(b) infrasound
(c) audible sound
(d) none of the above

5. Loudness or softness of a sound is depend on

(a) Amplitude
(b) Frequency
(c) Type of a wave
(d) None of these

6. Children under the age of 5 years can hear sound up to

(a) 10 kHz
(b) 20 2Hz
(c) 25 kHz
(d) 30 kHz

7. Sound is produced by ........objects.

(a) fast-moving
(b) vibrating
(c) stationary
(d) rotating

8. In case of transverse waves the particles of a medium vibrate:

(a) In the direction of wave propagation
(b) Opposite to the direction of wave propagation
(c) At the right angles to the direction of wave propagation
(d) None of the above

9. The upper-frequency limit of the audible range of human hearing is about

(a) 20 kHz
(b) 2000 Hz
(c) 2 kHz
(d) 2,000,000 Hz

10. Sonic booms are caused by the combination of

(a) supersonic speed and pressure variation.
(b) infrasonic speed and pressure variation.
(c) ultrasonic sound and pressure variation.
(d) pressure variation only.

11. The motion of the particles of a medium when a sound wave is passing through it is:

(a) translatory
(b) random
(c) rotatory
(d) oscillatory

12. The transfer of energy in a material medium due to the periodic motion of its particles is called:

(a) Wavefront
(b) Wave motion
(c) Pulse
(d) None of the above

13. Which wave property determines loudness?

(a) pitch
(b) frequency
(c) amplitude
(d) All of these

14. Sound cannot travel throug

(a) air
(b) water
(c) iron
(d) space

15. We can distinguish between a man’s voice and a woman’s voice of the same loudness even without seeing them. This is due to a characteristic of sound which measures the shrillness of sounds. Can you choose the correct unit of the quantity on which this characteristic of sound depends?

(a) hertz
(b) meter/second
(c) meter
(d) unitless

16. On increasing the temperature, the speed of sound in air:

(a) Increases
(b) Decreases
(c) Does not change
(d) First increases then becomes constant

17. The bats can fly in the darkness of night without colliding with the other objects by emitting special sounds while flying. Which characteristic of sound is used by the bats to navigate?

(a) Ultrasound
(b) Infrasound
(c) Audible sound
(d) None of these

18. Which of the following can produce longitudinal as well as transverse waves under different conditions?

(a) Bats
(b) Slinky
(c) Tuning fork
(d) None of these

19. If the speed of a wave is 380 m/s and its frequency is 1900 Hz, then the wavelength of the wave will be:

(a) 20 m
(b) 0.2 m
(c) 200 m
(d) 2 m

20. A part of a longitudinal wave in which particles of the medium are farther away than the normal particles is called:

(a) Rarefaction
(b) Trough
(c) Compression
(d) Crest 

Answer:

 1. Answer : (c) rhinoceros

Explanations: Rhinos have extremely good ears, picking up "infrasound" far deeper than the range of human hearing.

2. Answer : (a) ultrasonic waves

Explanations: Ultrasonic waves are used in SONAR instead of audible sound waves. SONAR uses ultrasonic waves i.e. sounds having a frequency greater than 20,000 Hz.

3. Answer : (b) amplitude

Explanations: Loudness is directly proportional to the amplitude of a sound. The larger the amplitude the louder the sound and the more energy the sound waves contain. Hence, when we change feeble sound to loud sound we increase its amplitude. Hence option B is the correct answer.

4. Answer : (b) infrasound

Explanations: Earthquake is basically the sudden movement of tectonic plates of the earth which causes tremor of earth crust and it produces infrasound before the main shock wave begins during this process there is a sudden release of seismic waves that makes the ground shake and these seismic waves are classed as infrasound waves.

5. Answer : (a) Amplitude

Explanations: The amplitude of a rope wave depends on how hard you shake it. For a sound wave, it depends on how much compression the loudspeaker or musical instrument creates. In other words, it depends on the energy the source put into the wave. It does not depend on frequency, wavelength, or velocity.

6. Answer : (c) 25 kHz

Explanations:  The children under age 5 years have fully developed inner and middle ears allowing them to hear from 20 Hz to 25,000 Hz. As age increases, our inner ear changes gradually which causes a reduction in hearing capacity from 20 Hz to 20,000 Hz.

7. Answer : (b) vibrating

Explanations:  Sound is produced by the vibration of an object. When an object vibrates back and forth in the air, then the molecules of air close to this object also start vibrating back and forth with the same frequency.

8. Answer : (c) At the right angles to the direction of wave propagation

Explanations: In a transverse wave when the wave moves forward, the particles of the medium vibrate perpendicular to the direction of motion of the wave.

9. Answer : (a) 20 kHz

Explanations: Humans can detect sounds in a frequency range from about 20 Hz to 20 kHz. (Human infants can actually hear frequencies slightly higher than 20 kHz, but lose some high-frequency sensitivity as they mature; the upper limit in average adults is often closer to 15–17 kHz.)

10. Answer : (a) supersonic speed and pressure variation.

Explanations: A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. As the object moves, this conical region also moves behind it and when the cone passes over the observer, they will briefly experience the boom. Sonic booms are caused by the combination of. supersonic speed and pressure variation.

11. Answer : (d) oscillatory

Explanations: In a transverse wave, the motion of the particles of the medium is at right angles (i.e., transverse) to the direction the wave moves. In a longitudinal wave, such as a sound wave, the particles oscillate along the direction of motion of the wave.

12. Answer : (b) Wave motion

Explanations: Wave motion is the propagation of a disturbance produced in a medium by the repeated periodic motion of the particles of the medium. In all progressive waves, energy travels through the medium in the direction in which the wave travels.

13. Answer : (c) amplitude

Explanations:  The amplitude of the wave is the maximum displacement of the particle from its mean position. It is the property, which determines the loudness of the sound. The amplitude and the loudness are directly proportional, i.e., the greater the amplitude the sound is characterized by a greater loudness.

14.Answer : (d) space

Explanations: Sound vibration must travel through matter. Sound cannot travel through a vacuum. A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.

15.Answer : (a) hertz

Explanations: The SI unit for frequency is the hertz (Hz). One hertz is the same as one cycle per second.

16.Answer : (a) Increases

Explanations: As the temperature increases the molecules in the air acquire more energy and the molecules vibrate faster. Since the molecules vibrate faster, the sound wave travels through the air faster because the sound wave is propelled by the collision of molecules in the air. 

17.Answer : (a) Ultrasound

Explanations: Bats are able to fly at night without colliding with other objects because they emit ultrasonic squeaks and listen to the echoes produced by the reflection of their squeaks from the objects or obstacles in their path.

18. Answer : (b) Slinky

Explanations: Slinky can produce longitudinal as well as transverse waves.

19. Answer : (b) 0.2 m

Explanations: velocity = frequency \(\times\) wavelength

⇒ 380 = 1900 \(\times\) wavelength

⇒ wavelength \(=\frac{380}{1900}\)

⇒ wavelength = \(\frac{38}{190}\)

⇒ wavelength = 0.2

20. Answer :  (a) Rarefaction

Explanations:  Rarefactions are areas of ultrasound wave having low pressure as the distance of their particles is far while compressions are areas having high pressure as the distance of their particles is close.

Click here to practice MCQ Questions of Sound class 9

n = f × t 

f = 290 Hz, 

t = 12 s 

n = 290 × 12 = 3480 times

below 20 Hz = Infrasonic

Above 20000 Hz = ultrasonic

i. A wave covers a distance equal to the wavelength (λ) during one period (T). 

Therefore, the magnitude of the velocity (v) is given by,

Magnitude of velocity = Distance covered/Corresponding time

ii. v = 22/7 i.e., v = λ × (1/T) .....(1)

iii. But reciprocal of the period is equal to the frequency (n) of the waves.

∴ 1/T = n ......(2)

iv. From equations (1) and (2), we get v = nλ

i.e., wave velocity = frequency × wavelength.

Principle : 

As waves don’t repulse each other, they overlap in the same region of the space without affecting each other. When two waves overlap, their displacements add vectorially.

Explanation : 

i. Consider two waves travelling through a medium arriving at a point simultaneously. 

ii. Let each wave produce its own displacement at that point independent of the others. This displacement can be given as, 

y₁ = displacement due to first wave. 

y₂ = displacement due to second wave. 

iii. Then according to superposition of waves, the resultant displacement at that point is equal to the vector sum of the displacements due to all the waves.

\(∴ \vec{y} = \vec{y_1} + \vec{y_2}\)

(C) elastic properties and density of the medium

i. Velocity of sound is directly proportional to square root of absolute temperature.

Hence, whistle’s sound will be first heard by Prakash in summer than in winter.

Therefore, the time interval between sound and train reaching Prakash in summer will be more than in winter.

i.e., t₁ > t₂

ii. When t = 33 °C

∴ v₁ = v₀ + 0.61t

= 330 + 0.61 × 33

∴ v₁ = 350.13 m/s

When t = 19 °C

v₂ = v₀ + 0.61t

= 330 + 0.61 × 19

v₂ = 341.59 m/s

True. 

At night, the amount of CO₂ in atmosphere increases the density of atmosphere. Since, Speed of sound is inversely proportional to the square root of density. 

Hence, speed of sound is greater during day than in night.

Correct option is: (A) 1450 m/s

s₁ = 300 m,

v₁ = 343 m/s,

∴ t₁ = \(\frac{s_1}{v_1}\) = \(\frac{300}{343}\) = 0.8746 s

Now,

s₂ = 5000 km = 5 × 10⁶ m,

v₂ = c = 3 × 10⁸ m/s

∴ t₂ = \(\frac{s_2}{c}\) = \(\frac{5\times10^6}{3\times10^8}\) = 0.0167 s

∴ t₂ < t₁

∴ Listener will hear the music first.

Time difference = t₁ – t₂

= 0.8746 – 0.0167

= 0.8579 s

The listener will hear the music first, about 0.8579 s before the person present at the concert.

Distance covered by the sound to reach boatman = 330ms^-1 × 3s = 990 m 

∴Distance of diver from the source of sound = 990m 990m 990 _ 

∴Time taken by the sound to reach diver = 1450ms^-1” 145s = 0.68s (Appox.).

(a) The two main difference are : 

Light Waves: 

1. They are electromagnetic waves and their velocity is 3 × 10⁸ms^-1. 

2. They have very small wavelength. 

Sound Waves: 

1. These are mechanical waves and their velocity is 340ms^-1. 

2. The wavelength of sound waves is quite large compared with that of light waves. 

(b) : 

1. Since loudness is inversely proportional to the square of the amplitude, I = loudness ∝ 1/(amp)² therefore loudness will be in ratio of (2)² : (3)² i.e., 4 : 9. 

2. Since their pitch is the same, therefore their frequencies will be same i.e., their ratio is 1 : 1. 

(c) : 

1. Loudness 

2. Colour

The time t after which an echo is heard is given by,= 0.07s which is less than. 1s.

The object due to which sound is produced is called the source of the sound.

1. Vocal cords 

2. Lips 

3. Teeth and tongue 

4. Nose and throat

The science of sound, resonance, production, propagation and effects of sound is called acoustics.

The vibration of the vocal chords in our larynx or voice box produces sound.

B) rough, smooth

The vibration of the vocal chords in our larynx or voice box produces sound.

Correct option is C) SONAR

Correct option is A) SONAR

C) ultrasonography

B) more than 0.1s

Ultrasonic: Sound of frequency greater than 20 kHz is known as ultrasonic sound.

Sonic: Of or relating to audible sound. e.g : a sonic wave.

Quality of sound: The quality of sound is the characteristic that enables us to distinguish between musical notes emitted by different musical instruments.

Wavelength: The distance between two consecutive compressions or two consecutive rarefactions is called the wavelength of a sound wave.

Pressure: Pressure is force per unit area applied in a direction .perpendicular to the surface of an object. 

The SI unit of pressure is the newton per square meter, which is called the pascal (Pa) after the seventeenth-century philosopher and scientist Blaise Pascal.