CBSE Class 9 Science Sound MCQs Set B

Question: The highest frequency produced by a man is 1700 Hz and that of a woman is 2780 Hz. The ratio of wavelengths of the sound of man and woman are (speed of sound is 340 m/s)
a) 1: 0.60
b) 1: 0.61
c) 1: 062
d) 1: 0.59
Answer: b

Question: The loudness of a whisper is
a) 10 dB
b) 20 dB
c) 30 dB
d) 40 dB
Answer: b

Question: The speed of sound at 25 oC is
a) 331 m/s
b) 344 m/s
c) 346 m/s
d) 350 m/s
Answer: c

Question: Which wave cannot be polarised?
a) longitudinal waves.
b) transverse waves.
c) both longitudinal waves and transverse waves.
d) none of the options.
Answer: a

Question: Which of the following is an elastic wave?
a) Sound waves
b) Light waves
c) X-rays
d) Radio waves
Answer: a

Question: Human heart beats about 72 times in a minute. So the frequency of the heartbeat is
a) 1.5 Hz
b) 1.4 Hz
c) 1.2 Hz
d) 2.25 Hz
Answer: c

Question: The loudness of a sound is measured in
a) hertz.
b) meter.
c) second
d) decibel.
Answer: d

Question: At the end of the auditory canal, there is a thin membrane called
a) hammer.
b) pinna
c) anvil.
d) eardrum.
Answer: d

Question: The sound waves travel fastest in
a) solids.
b) liquids.
c) gases.
d) vacuum.
Answer: a

Question: Which of the following device does not work on the multiple reflections of sound waves?
a) Stethoscope
b) Hydrophone
c) Soundboard
d) Megaphone
Answer: b

Question: Which is called a whispering gallery in India?
a) Taj Mahal
b) Gol Gumbaj
c) Swarna Mandir
d) Ajanta Caves
Answer: b

Question: A man stands between two cliffs and fires a gun. He hears two successive echoes after 3 s and 5 s. The distance between the two cliffs is
a) 1320 m
b) 1315 m
c) 1312 m
d) 1310 m
Answer: a

Question: We can recognise the voice of our family members without seeing them because the voice of each member has a particular
a) pitch.
b) loudness.
c) quality.
d) frequency.
Answer: c

Question: Which one of the following properties of sound is affected by change in the air temperature?
a) Frequency
b) Amplitude
c) Intensity
d) Wavelength
Answer: d

Question: A constant hearing of noise in the range of may result in the loss of hearing or deafness.
a) 100–110 dB
b) 110–120 dB
c) 130–140 dB
d) 90–110 dB
Answer: c

Question: The speed of sound wave in air is
a) 330 m/s
b) 332 m/s
c) 340 m/s
d) 350 m/s
Answer: b

Question: Sounds having frequency less than 20 Hz are known as
a) audible sounds.
b) ultrasound
c) notes.
d) inaudible sounds.
Answer: d

Question: Which does not move with a supersonic sound?
a) Bullet fired from a gun
b) Jet aircraft
c) Rocket
d) Helicopter
Answer: d

Question: Galton’s whistle can produce sound more than
a) 500 Hz
b) 1000 Hz
c) 2000 Hz
d) 1500 Hz
Answer: c

Question: The distance between a crest and an adjacent trough is equal to
a) the wavelength.
b) half the wavelength.
c) one-fourth the wavelength .
d) twice the wavelength.
Answer: b

Question: In SONAR we use
a) ultrasonic waves.
b) infrasonic waves.
c) radio waves.
d) audible sound waves.
Answer: a

Question: When the skin of a tabla or the strings of a guitar are tightened, they produce a sound of higher .
a) quality
b) loudness
c) pitch
d) wave length
Answer: c

Question: A slinky can produce in laboratory
a) transverse waves only.
b) longitudinal waves only.
c) both transverse waves only and longitudinal waves only
d) none of the options
Answer: c

Question: The technique of obtaining images of the heart of the body by using ultrasonic waves is called
a) ultrasonography.
b) echocardiography.
c) x-ray.
d) cardiograph.
Answer: b

Question: An object moving at a speed greater than that of sound is said to be moving at
a) supersonic speed
b) sonic speed
c) infrasonic speed
d) ultrasonic speed
Answer: b

Question: A medical instrument used to detect and study sounds produced within organs such as the heart and lungs prior to treatment is called
a) stethoscope.
b) ultrasound
c) sound boards.
d) megaphone.
Answer: a

Question: A wave source produces 20 crests and 20 troughs in 0.2 second) The frequency of the wave is
a) 200 Hz
b) 500 Hz
c) 300 Hz
d) 100 Hz
Answer: d

Question: The voice of children and women is shrill because
a) children and women have short vocal cords.
b) vocal cords vibrate with high frequency.
c) they produce a high-pitched voice.
d) all of these.
Answer: d

Question: Which one is not a fundamental characteristic of a sound?
a) Pitch
b) Frequency
c) Loudness
d) Quality
Answer: b

 Question: The minimum distance from a sound–reflecting surface to hear an echo is
a) 17.5 m
b) 17.4 m
c) 17.2 m
d) 17 m
Answer: c