Question 3 :
<p>If pitch of a sound is pleasing to our ears, the sound is:</p>

Question 5 :
The amplitude of vibration and its frequency can change suddenly in a:

Question 9 :
While travelling by train, when the train passes through the tunnel, why does our ear aches ?

Question 10 :
In the following sentence. say 'True' and 'False'<br/>$(a)$ Sound can't travel in vacuum (T/F)<br/>$(b)$ The number of oscillations per second of a vibrating object is called its time period. (T/F)<br/>$(c)$ If the amplitude of vibration is large, sound is feeble. (T/F)<br/>$(d)$ For human ears, the audible range is 20Hz to 20,000Hz. (T/F)<br/>$(e)$ The lower the frequency of vibration, the higher is the pitch.<br/>$(f)$ Unwanted or unpleasant sound is termed as music. (T/F)<br/>$(g)$ Noise pollution may cause partial hearing impairment. (T/F)

Question 14 :
<p>Which of the following measure can be taken to control noise pollution in our surroundings.</p>

Question 17 :
Which of the following is not caused due to noise pollution?

Question 18 :
To reduce noise pollution, which of the following devices must be installed on the vehicles ?

Question 19 :
Which of the following are true for noise pollution?<br/>a)&#160;Noise pollution is unpleasant and discomforting.<br/>b)&#160;Noise pollution can cause health problems.<br/>c)&#160;Long term exposure to loud noises can cause temporary or ever&#160;permanent hearing impairment.d)&#160;Noise pollution is caused by extremely loud sounds.

Question 23 :
Presence of excessive or unwanted sounds in the environment is called&#160;

Question 24 :
State whether given statement is True or False<br/>Noise pollution can cause partial hearing impairment. <br/>

Question 26 :
State whether given statement is True or False :<br/>Sound from outer space adds to the noise pollution on the earth.<br/>

Question 27 :
Which of the following is / are effective for preventing noise pollution?<br/>

Question 28 :
State whether given statement is True or False<br/>Water animals are also subjected to noise pollution.<br/>

Question 29 :
Trees must be removed from the road sides and around buildings to reduce the harmful effects of noise pollution.

Question 30 :
Select the odd one out (loudspeakers, aeroplanes, vacuum cleaners, ear plugs)

Question 31 :
When we hold a thin plastic ruler firmly on a bench:

Question 32 :
Assertion: In the case of a stationary wave, a person hear loud sound at the nodes as compared to the antinodes. Reason: In a stationary wave all the particles of the medium vibrate in phase.

Question 34 :
The membrane of a drum vibrates to produce sound. Similarly the string of a sitar vibrates to produce sound. Based on these two examples answer the following question. Which part of a whistle vibrates to produce sound?

Question 35 :
Different musical instruments sound different even when they play a note with the same pitch.

Question 36 :
A key of a mechanical piano struck gently and then struck again but muchharder this time. In the second case<br>

Question 38 :
The sound waves which cannot be heard by a human ear are called.

Question 39 :
A source of wave produce 1 crest and 1 trough in 16s. Find the frequency of the wave.