Class 8 Science Chapter 11 Practice Question Answers - Sound

Q1: What does voice box or larynx of human produces?
Ans: Sound

Q2: In which medium sound propagates the maximum?
Ans: Solid

Q3: Name the sound producing organ in human.
Ans: Larynx

Q4: What is vibration?
Ans: Back and forth motion of an object.

Q5: Do all bodies produce sound?
Ans: No

Q6: How is sound produced?
Ans: By vibrating bodies.

Q7: Name a musical instrument which produces sound by blowing air into it.
Ans: Flute

Q8: What is the unit of frequency?
Ans: Hertz

Q9: Human beings sound is produced by __________.
Ans: larynx

Q10: Sound of frequency lower than 20 Hz is called the __________.
Ans: infrasonic

Q11: The __________ nerve is also present in the inner ear.
Ans: auditory

Q12: Sounds which are unpleasant to the ear is called __________.
Ans: noise

Q13: Too much noise in our surroundings that causes discomfort is called __________.
Ans: noise pollution

Q14: The speed of sound is maximum in __________.
Ans: solids

Q15: The voice box is also called as
(a) stomach
(b) heart
(c) larynx
(d) mouth
Ans: (c)
Explanation: The voice box, which is responsible for producing sound and controlling pitch, is known as the larynx. It contains vocal cords that vibrate to generate sound when air passes through them.

Q16: Sound is a kind of
(a) work
(b) energy
(c) force
(d) pressure
Ans: (b)
Explanation: Sound is a form of energy that is produced by vibrations and transmitted through a medium (such as air, water, or solids) in the form of waves. These waves carry energy from the source of vibration to the surrounding environment.

Q17: The hearing range of 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
Ans: (a)
Explanation: The typical hearing range of the human ear is approximately 20 Hz to 20,000 Hz (Hertz). This range covers the frequencies of sound waves that humans are capable of perceiving as audible sound.

Q18: Pitch of sound is determined by its
(a) frequency
(b) speed
(c) amplitude
(d) loudness
Ans: (a)
Explanation: The pitch of sound refers to how high or low a sound is perceived. The pitch is determined by the frequency of the sound wave. Higher frequency sound waves result in higher-pitched sounds, while lower frequency sound waves result in lower-pitched sounds.

Q19: 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
Ans: (c)
Explanation: Subsonic sound refers to sound waves with frequencies that are below the audible range of human hearing, which is generally considered to be 20 Hz and above. Therefore, subsonic sound frequencies are typically less than 20 Hz.

Value-Based Questions

Q20: On Ramesh’s 13th birthday, his father invited all his friends and their relatives. It was a big party with lots of food and DJs. Ramesh didn’t like the loud sound of DJs and asked his father to play it in a low volume so that their neighbours do not get much disturbed and people in the party can also enjoy the music. Ramesh’s father felt good for his wisdom and did as he said.

1. Do you enjoy loud sound DJs in parties?
2. Do you think when loud music is played in a party is acceptable to all the people living in , neighbourhood?
3. How can you control noise pollution at your end?
4. What value of Ramesh is shown here?

Ans:

1. Yes/No (according to your choice)
2. No, it may be not acceptable to all the people living in neighbourhood.
3. We can control noise pollution at our end by:
   • not playing music loudly.
   • planting trees around house.
   • cushioning gaps in windows and doors.
   • using ear plugs at noisy places.
   • doing meditation.
4. Ramesh is wise, mature, knows hazards of noise pollution, concern about others and good-hearted.