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Sound Class 9 MCQs Questions with Answers
Solving the Sound Multiple Choice Questions of Class 9 Science Chapter 12 MCQ can be of extreme help as you will be aware of all the concepts. These MCQ Questions on Sound Class 9 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Have a glance at the MCQ of Chapter 12 Science Class 9 and cross-check your answers during preparation.
Multiple Choice Questions
Question 1.
For hearing a distinct sound, the time interval between the original sound and the reflected one must be at least:
(a) 1 s
(b) 0.1 s
(c) 2 s
(d) 0.2 s
Answer
Answer: (b) 0.1 s
Question 2.
The persistence of sound in an auditorium is the result of repeated reflections of sound and is called:
(a) reverberation
(b) audible
(c) distinct sound
(d) reflection
Answer
Answer: (a) reverberation
Question 3.
The speed v, frequency υ, and wavelength λ, of sound are related by the equation:
(a) v = λυ
(b) υ = λv
(c) λ = υv
(d) v = \(\frac{\lambda}{υ}\)
Answer
Answer: (a) v = λυ
Question 4.
The speed of sound is maximum in:
(a) solids
(b) liquids
(c) gases
(d) All of these
Answer
Answer: (a) solids
Question 5.
Our ears are sensitive to sound frequencies between:
(a) 20 Hz to 20 kHz
(b) 2 Hz to 20 Hz
(c) 20 kHz to 200 kHz
(d) 2000 kHz to 20000 kHz
Answer
Answer: (a) 20 Hz to 20 kHz
Question 6.
Which of the following waves are produced by bats?
(a) Infrasonic waves
(b) Ultrasonic waves
(c) Audible waves
(d) All of these
Answer
Answer: (b) Ultrasonic waves
Question 7.
Maximum tolerable sound is:
(a) 0 dB
(b) 10 dB
(c) 60 dB
(d) 120 dB
Answer
Answer: (d) 120 dB
Question 8.
Sound waves are:
(a) magnetic waves
(b) electric waves
(c) electromagnetic waves
(d) mechanical waves
Answer
Answer: (d) mechanical waves
Question 9.
In SONAR, we use:
(a) ultrasonic waves
(b) infrasonic waves
(c) radio waves
(d) audible sound waves
Answer
Answer: (a) ultrasonic waves
Question 10.
Sound travels in the air if:
(a) particles of medium travel from one place to another
(b) there is no mixture in the atmosphere
(c) disturbance moves
(d) both particles as well as disturbance travel from one place to another
Answer
Answer: (c) disturbance moves
Question 11.
When we change feeble sound to loud sound we increase its:
(a) frequency
(b) amplitude
(c) velocity
(d) wavelength
Answer
Answer: (b) amplitude
Question 12.
In the curve half the wavelength is:
(a) AB
(b) BD
(c) DE
(d) AE
Answer
Answer: (b) BD
Question 13.
An earthquake produces which kind of sound before the mainshock wave begins:
(a) ultrasound
(b) infrasound
(c) audible sound
(d) None of the above
Answer
Answer: (b) infrasound
Question 14.
Infrasound can be heard by:
(a) dog
(b) bat
(c) rhinoceros
(d) human beings
Answer
Answer: (c) rhinoceros
Fill in the blanks.
Question 15.
Sound travels as a _______ wave through a material medium.
Answer
Answer: longitudinal
Question 16.
The change in density from one maximum value to the minimum value and again to the maximum value makes one complete ________
Answer
Answer: oscillation
Question 17.
Sound waves with frequencies below the audible range are termed as ________
Answer
Answer: infrasonic
Question 18.
Sound waves with frequencies above the audible range are termed as ________
Answer
Answer: ultrasonic
Question 19.
________ is produced due to reflections of sound from obstacles.
Answer
Answer: Echo
Question 20.
Wave velocity = Frequency × ________
Answer
Answer: wavelength
Question 21.
Sound frequencies greater than 20,000 Hz are known as ________
Answer
Answer: ultrasonic sound
Question 22.
Echo can be heard clearly if the minimum distance between the source of the sound and the obstacle is ________
Answer
Answer: 17.2 meter
Question 23.
Echo is produced due to _______ of sound from obstacles.
Answer
Answer: reflection
True/False.
Question 24.
Sound is produced due to the vibration of different objects.
Answer
Answer: True
Question 25.
Sound travels as successive compressions and rarefactions in the medium.
Answer
Answer: True
Question 26.
In sound propagation, it is the energy of the sound that travels and not the particles of the medium.
Answer
Answer: True
Question 27.
Sound propagates in a vacuum.
Answer
Answer: False
Question 28.
The speed of sound does not depend primarily on the nature and the temperature of the transmitting medium.
Answer
Answer: False
Question 29.
Loudness is a physiological response of the ear to the intensity of sound.
Answer
Answer: True
Question 30.
The audible range of hearing for average human beings is in the frequency range of 20Hz – 20kHz.
Answer
Answer: True
Question 31.
Sound frequencies above 20 Hz are known as inaudible sound.
Answer
Answer: False
Question 32.
Rhino can hear the sound frequency of 5 Hz.
Answer
Answer: True
Question 33.
SONAR is used to determine the depth of the sea.
Answer
Answer: True
Question 34.
The transverse and longitudinal waves are called progressive waves.
Answer
Answer: True
Match the Column.
Question 35.
| A | B |
| 1. Frequency below 20 Hz | (i) 120 dB |
| 2. Heartbeat | (ii) Audible sounds |
| 3. Maximum tolerable sound | (iii) Infrasonic sounds |
| 4. Frequency of 20 Hz to 20,000 Hz | (iv) Stethoscope |
| 5. Uses of SONAR | (v) Decibel |
| 6. The unit of intensity of sound | (vi) Depth of sea |
Answer
Answer:
| A | B |
| 1. Frequency below 20 Hz | (iii) Infrasonic sounds |
| 2. Heartbeat | (iv) Stethoscope |
| 3. Maximum tolerable sound | (i) 120 dB |
| 4. Frequency of 20 Hz to 20,000 Hz | (ii) Audible sounds |
| 5. Uses of SONAR | (vi) Depth of sea |
| 6. The unit of intensity of sound | (v) Decibel |
Answer in Word/Sentence.
Question 36.
What is the term given to the distance between two consecutive compression or two consecutive rarefactions?
Answer
Answer: Wavelength (λ)
Question 37.
What is the term given to the time taken by the wave for one complete oscillation of the density of the medium?
Answer
Answer: Time Period (T)
Question 38.
What is the amount of sound energy passing each second through the unit area?
Answer
Answer: The intensity of sound
Question 39.
Which technique is used to locate underwater hills, valleys, submarines, icebergs, sunken ships, etc.?
Answer
Answer: The SONAR
Question 40.
What type of mechanical waves are produced in the air (gases)?
Answer
Answer: Longitudinal waves
Question 41.
What type of mechanical waves are produced on the surface of the water?
Answer
Answer: Transverse waves
Question 42.
What type of waves are sound waves?
Answer
Answer: Longitudinal mechanical waves
Question 43.
What type of waves are produced by the bats while flying?
Answer
Answer: Ultrasound waves
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