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NCERT solutions Science Textbook For Class 8 chapter 13 Sound

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Chapter 13 - Sound

Pages 168 - 169

Choose the correct answer.

Sound can travel through

(a) gases only

(b) solids only

(c) liquids only

(d) solids, liquids and gases.

Q 1 | Page 168 |

Which of the following voices is likely to have minimum frequency?

(a) Baby girl

(b) Baby boy

(c) A man

(d) A woman

Q 2 | Page 168 |

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.

Sound cannot travel in vacuum. (T / F)

Q 3.1 | Page 169 |

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false

The number of oscillations per second of a vibrating object is called its time period. (T / F)

Q 3.2 | Page 169 |

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.

If the amplitude of vibration is large, sound is feeble. (T / F)

Q 3.3 | Page 169 |

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false

For human ears, the audible range is 20 Hz to 20,000 Hz. (T / F)

Q 3.4 | Page 169 |

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.

The lower the frequency of vibration, the higher is the pitch. (T / F)

Q 3.5 | Page 169 |

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.

Unwanted or unpleasant sound is termed as music. (T / F)

Q 3.6 | Page 169 |

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false

Noise pollution may cause partial hearing impairment. (T/F)

Q 3.7 | Page 169 |

Fill in the blanks with suitable words.

Time taken by an object to complete one oscillation is called _________.

Q 4.1 | Page 169 |

Fill in the blanks with suitable words.

Loudness is determined by the ________ of vibration.

Q 4.2 | Page 169 |

Fill in the blanks with suitable words.

The unit of frequency is _________.

Q 4.3 | Page 169 |

Fill in the blanks with suitable words.

Unwanted sound is called _________.

Q 4.4 | Page 169 |

Fill in the blanks with suitable words.

Shrillness of a sound is determined by the _________ of vibration

Q 4.5 | Page 169 |

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

Q 5 | Page 169 |

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?

Q 6 | Page 169 |

Identify the part which vibrates to produce sound in the following instrument.

Dholak

Q 7.1 | Page 169 |

Identify the part which vibrates to produce sound in the following instrument

Sitar

Q 7.2 | Page 169 |

Identify the part which vibrates to produce sound in the following instrument

Flute

Q 7.3 | Page 169 |

What is the difference between noise and music? Can music become noise sometimes?

Q 8 | Page 169 |

List sources of noise pollution in your surroundings.

Q 9 | Page 169 |

Explain in what way noise pollution is harmful to humans.

Q 10 | Page 169 |

Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.

Q 11 | Page 169 |

Sketch larynx and explain its function in your own words.

Q 12 | Page 169 |

Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. Can you explain?

Q 13 | Page 169 |

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