Question

chapter 12 dav science class 8​

Answer 1

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1. tracheal cartilage

2. decibel

3. frequency

4. ultrasonic sounds

5. Noise

Answer 2

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1. Birds have a ring of cartilage, called syrinx in their wings pipes.
2. The SI unit of 'loudness' of sound is decibels (dB) .
3. The pitch of a sound is determined by its frequency.
4. Sound, of frequency more than 20 kHz, are known as ultrasound.
5. An irregular, irritating sound is referred to as a noise.

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1. Syrinx
2. Decibels (dB)
3. Frequency
4. Ultrasound
5. Noise