# Class 9 Science Important Questions for Sound

Given below are the Class 9 Science Important Questions and worksheet for Sound
(b) Match thec column
(c) Fill in the blanks
(d) Crossword Puzzle

## Very Short Answer Based questions

Question 1
1. Arrange the speed of sound in Steel, water and air in ascending order?
2. What is the relation between frequency and time period of the wave?
3. Sound waves are transverse waves True or False?
4. Arrange the speed of these waves in air in descending order   a) light  b) Sound c) Supersonic aircraft?
5. What is an echo?
6. What are three characteristics of the sound
7. What is the audible range of sound frequencies for human ear?
8. What is Reflection of sound?

Question 2

## Fill in the blanks

Question 3
(i)Sound waves   ……  travel in vacuum
(ii)The speed of sound depends on   ………….  And  …………
(iii)The soft and porous materials are bad  ………. Of sound
(iv)The speed of the highly penetrating ultrasonic waves are   …………………..  those of audible sound waves
(v) The ……….. sound are produced before the main shock wave of earth quake

## Crossword Puzzle

Question 4
Across
4. It is used break kidney stones into fine grains
7. The unit of frequency
8. The loudness of the sound depends on this
9. Medical instrument used by the doctors for listening to heartbeats
10. It is the region of low pressure in longitudinal wave
Down
1. Apparatus used to find the depth of the sea
2. It converts sound wave frequency into electrical impulses
3. A vibrating simple pendulum produces this type of sound
5. It is the sensation of a frequency
6. Elevation in a transverse wave

Question 5
Why Sometimes we hear echo of sound.

Question 6
What is a wave number?

Question 7
Are Sound waves mechanical waves?

Question 8
A vibrating body produces sound. However, no sound is heard when a simple pendulum oscillates in air why?