Q. Explain in what way noise pollution is harmful to humans.

Q. Sketch larynx and explain its function in your own words :

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

Q. In the following statements, tick T against those which are true, and F against those which are false:
(a) Sound cannot travel in vacuum. (T/F)
(b) The number of oscillations per second of a vibrating object is called its time period. (T/F)
(c) If the amplitude of vibration is large, sound is feeble. (T/F)
(d) For human ears, the audible range is $20Hz$ to $20,000Hz$. (T/F)
(e) The lower the frequency of vibration, the higher is the pitch. (T/F)
(f) Unwanted or unpleasant sound is termed as music. (T/F)
(g) Noise pollution may cause partial hearing impairment. (T/F)

Q. List sources of noise pollution in your surroundings.

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

Q. 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. 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. Fill in the blanks with suitable words.
(a) Time taken by an object to complete one oscillation is called _________ .
(b) Loudness is determined by the __________ of vibration.
(c) The unit of frequency is __________ .
(d) Unwanted sound is called ___________ .
(e) Shrillness of a sound is determined by the __________ of vibration.

Q. Identify the part which vibrates to produce sound in the following instruments:
(a) Dholak
(b) Sitar
(c) Flute

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

1. Baby girl
2. A man
3. A woman
4. Baby boy

Q. 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?