NCERT Class-9 Science Solutions: Chapter 12-Sound Part 1

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Multiple Choice Questions

Question 1:

Note is a sound

  1. Of mixture of several frequencies

  2. Of mixture of two frequencies only

  3. Of a single frequency

  4. Always unpleasant to listen

Answer: A

Image the mixture of several frequencies

Image the Mixture of Several Frequencies

Image the mixture of several frequencies

Question 2:

A key of a mechanical piano struck gently and then struck again but much harder this time. In the second case

  1. Sound will be louder but pitch will not be different

  2. Sound will be louder and pitch will also be higher

  3. Sound will be louder but pitch will be lower

  4. Both loudness and pitch will remain unaffected

Answer: A

Image Sound will be louder but pitch

Image Sound Will Be Louder but Pitch

Image Sound will be louder but pitch

Question 3:

In SONAR, we use

  1. Ultrasonic waves

  2. Infrasonic waves

  3. Radio waves

  4. Audible sound waves

Answer: A

Image In SONAR, we use Ultrasonic waves

Image in SONAR, We Use Ultrasonic Waves

Image In SONAR, we use Ultrasonic waves

Question 4:

Sound travels in air if

  1. Particles of medium travel from one place to another

  2. There is no moisture in the atmosphere

  3. Disturbance moves

  4. Both particles as well as disturbance travel from one place to another.

Answer: C

Image Sound travels in air

Image Sound Travels in Air

Image Sound travels in air

Question 5:

When we change feeble sound to loud sound we increase its

  1. Frequency

  2. Amplitude

  3. Velocity

  4. Wavelength

Answer: B

Image the Amplitude

Image the Amplitude

Image the Amplitude

Question 6:

In the curve (Figure) half the wavelength is

  1. A B

  2. B D

  3. D E

  4. A E

Image the curve

Image the Curve

Image the curve

Answer: B

Question 7:

Earthquake produces which kind of sound before the main shock wave begins

  1. Ultrasound

  2. Infrasound

  3. Audible sound

  4. None of the above

Answer: B

Image earthquake produces Infrasound

Image Earthquake Produces Infrasound

Image earthquake produces Infrasound