# NCERT Solutions for Class 8 Science Chapter 13 Sound

NCERT Solutions for Class 8 Science Chapter 13 Sound are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 13 Sound.

 Board CBSE Textbook NCERT Class Class 8 Subject Science Chapter Chapter 13 Chapter Name Sound Number of Questions Solved 13 Category NCERT Solutions

## NCERT Solutions for Class 8 Science Chapter 13 Sound

NCERT TEXTBOOK EXERCISES

Question 1.
Sound can travel through
(a) gases only
(b) solids only
(c) liquids only
(d) solids, liquids and gases
(d) solids, liquids and gases.

Question 2.
Voice of which of the following is likely to have minimum frequency?
(a) Baby girl
(b) Baby boy
(c) A man
(d) A woman
(b) Baby boy.

Question 3.
In the following statements, tick âTâ against those which are true, and âFâ against those which are false:

1. Sound cannot travel in a vacuum. (T/F)
2. The number of oscillations per second of a vibrating object is called its time period. (T/F)
3. If the amplitude of vibration is large, the sound is feeble. (T/F)
4. For human ears, the audible range is 20 Hz to 20,000 Hz. (T/F)
5. The lower the frequency of vibration, the higher is the pitch. (T/F)
6. Unwanted or unpleasant sound is termed music. (T/F)
7. Noise pollution may cause partial hearing impairment. (T/F)

1. True
2. False
3. False
4. True
5. False
6. False
7. True

Question 4.
Fill in the blanks with suitable words:

1. Time taken by an object to complete one oscillation is called…….
2. Loudness is determined by the………..of vibration.
3. The unit of frequency is………….
4. Unwanted sound is called……….
5. The shrillness of a sound is determined by the.……….of vibration.

1. time period
2. amplitude
3. Hertz (Hz)
4. noise
5. frequency.

Question 5.
A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

Question 6.
The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?
Number of vibrations per second = 500
Time period = time is taken for one vibration

Question 7.
Identify the part which vibrates to produce sound in the following instruments:

1. Dholak
2. Sitar
3. Flute

1. Stretched membrane
2. String of sitar
3. Air column.

Question 8.
What is the difference between noise and music? Can music become noise sometimes?
The unpleasant sound is called noise, whereas a pleasant sound is called music. Noise can produce so many health hazards, whereas music brings about a soothing effect. Yes, music can become noise sometimes when the musical instruments produce very high volume sounds.

Question 9.
List sources of noise pollution in your surroundings.
Following are the major sources of noise pollution:

1. Sounds of vehicles.
2. Sounds of the bursting of crackers and explosives.
3. Sounds of loudspeakers, TVs, transistors.
4. Sounds of kitchen appliances.
5. Sounds of desert coolers, air conditioners etc.

Question 10.
Explain in what way noise pollution is harmful to humans.
Noise pollution may cause many health-related problems.

• Lack of sleep, hypertension (high blood pressure), anxiety, etc. are some of the problems that may be caused due to noise pollution.
• A person who is exposed to a loud sound continuously may get temporary or even permanent deafness.

Question 11.