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Class 9 Science MCQ Questions of Sound with Answers?

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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 

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 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.

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