When a train enters a tunnel, it compresses the air in front of it like a piston. Unlike outside air, air in a tunnel can’t be simply pushed aside—the tunnel walls are in the way. Some of the air is pushed forward, all the way down to the tunnel’s other end, but most of it rushes through the narrow space between the train and the tunnel walls, filling in the area behind the train. Being forced into this narrow space makes the air rush faster, exactly as water speeds up at the base of a funnel. In fact, this tunnel air can rush backward much faster than the train’s forward speed. his fast moving air creates a kind of suction on the train, lowering the air pressure inside and making your ears go pop. It cause ear aches

Hence, due to sudden increase and decrease pressure inside tunnel, aches occur in ear 

Musical sound is produced by regular vibration where as noise is produced by irregular vibration.

$Answer:-$ C

Noise pollution is hazardous to health in many ways as it can cause insomnia, hypertension and hearing impairment.

Materials which are soft , porous and have a high sound absorption coefficient , are good absorber of sound , thermocol has these qualities , so it is a good absorber of sound .

Pitch is a characteristic of sound , which depends upon frequency and amplitude of vibration doesn't affect it .

Below are the answers and the corresponding explanations.

(a) True. Sound requires a medium to travel through. Since vacuum is devoid of any medium, sound cannot travel through it.

(b) False. The number of oscillations per second of a vibrating object is known as its frequency. Time period is the time
required to complete one oscillation.

(c) False. Loudness of a sound is proportional to the square of the amplitude of its vibration. When the amplitude of
vibration of a sound is large, the sound is very loud. The sound is feeble for small amplitude.

(d) True. Humans cannot hear sounds of all frequencies. Human can hear a sound whose frequency falls in the range of
20 Hz - 20,000 Hz. The sound having frequency out of this range is inaudible to humans.

(e) False. The pitch of a sound is proportional to its frequency. As the frequency of vibration increases,
the pitch of the sound also increases and vice versa. A sound is said to be high pitched if its frequency of vibration is high
and is low pitched for a small frequency of vibration.

(f) False. Unwanted or unpleasant sounds are known as noise. Sounds that are melodious and pleasing to ear are known as music.

(g) True. Unwanted or unpleasant sounds are known as noise. If one is subjected to loud unpleasant sound
continuously for a long time, then it may cause temporary hearing impairment.

Trees absorb and block noise and reduce glare. A well placed tree can reduce noise by as much as 40 percent.
Hence, the statement is False.

Ear plugs prevent sound pollution others are sources of noise pollution

Except loud speaker all are preventive measures of noise pollution while loud speaker creates noise pollution

Sounds that are unpleasing and disturbing to the ears are called noise, whereas, the pleasing and comforting to the ears are called music, like those produced by musical instruments.

Too much and too loud sounds in the environment cause noise pollution. Noise pollution can be harmful for the health of people.

The sounds from factories, fire crackers, aircraft, etc. are much above $80$ dB, which is the level above which noise causes discomfort and becomes physically painful.

It is very important to reduce noise pollution since it may cause serious health problems. Thus, various methods have to be adopted to reduce noise pollution like minimizing the sound coming from T.V., radio, etc., silencing automobiles, creating factories only in industrial areas, planting trees to block the noise etc.

Noise pollution is caused by extremely loud sounds and is very discomforting and painful for the ears. It may also cause health problems like hypertension, lack of sleep, anxiety and many more. Also, continuous exposure to loud sounds can cause temporary or permanent hearing defect.

Noise pollution can be reduced by using silencers in vehicles, industrial machines, and home appliances reducing use of vehicle horns, running TV, radio and music systems at low volumes. Planting of trees along roads and buildings also help to reduce noise pollution.

Noise pollution can lead to a number of health-related problems. Some of them are as follows:
(i) Hearing loss

Trees absorb the sound vibrations produced by various sources and hence leading in prevention of noise pollution. It also provide shades and make the roads beautiful.

Wavelength is not a characteristic of musical sound. Pitch, Quality and Loudness are all characteristics of a musical sound.

Noise pollution can be reduced by using silencers in vehicles, industrial machines, and home appliances reducing use of vehicle horns, running TV, radio and music systems at low volumes. Planting of trees along roads and buildings also help to reduce noise pollution

noise pollution can lead to a number of health-related problems. Some of them are as follows:

 (i) Hearing loss  

(ii)Inability to sleep    

(iii) Hypertension

(iv) A severe headache

 (v) Stress

Trees are planted along the roads and around buildings so that it could cut off sound vibrations produced from vehicles speakers etc. by absorbing them, hence leading in prevention of Noise pollution.

Music for a person depends upon the nature , feelings and mood of the person , therefore music for one person can be noise for others .

Lights in a vehicle are used to experience the  view ahead of vehicle , in low light .

Music is a pleasant sound, whereas noise is unpleasant to hear. The waveform of musical sound is periodic and regular whereas the waveform of noise is irregular and sudden.
The frequencies that make up a musical sound are in the ratio of small whole numbers whereas this is not the case for noise.

Pollution is that , which harms our environment or health of animals on earth , excessive unwanted sounds are harmful to ear , therefore it is called noise pollution .

Diabetes is not caused by noise pollution , as diabetes is caused due to lack of insulin in human body . 

The characteristics of musical sound are:

(i) loudness (intensity)

(ii) pitch (frequency)

(iii) quality (overall effect of all the harmonics present in the sound).

Sound from outer space does not reach the earth surface as there is vacuum in the outer space. Obviously the sound from outer space can not add up to the noise pollution on the earth.

Music is harmonious sound described as high frequency, regular waveform and with no sudden changes in amplitude or wavelength.

All the steps mentioned are effective ways, among others, for preventing noise pollution.

Yes. Water animals are affected by submarines and other vehicles which travel through the sea or ocean creating loud sound waves in water.

Noise pollution can cause partial hearing impairment to human ears.

All the given ones, among others, are effective sources of noise pollution.

The statement is true. Any sound, music or noise, above $65\ dB$ of loudness, is harmful and damaging to human ears.

Pitch of music is pleasing to our ears.

Amplitude is the maximum distance moved by medium particles on either side of mean position.

1) Pitch is defined as the perceived fundamental frequency of sound.

2) Tone is defined as the quality of sound.

Smooth and periodic vibration is music and irregular and non-periodic vibration is noise.

Sounds can be harmful when they are too loud, even for a brief time, or when they are both loud and long-lasting. These sounds can damage sensitive structures in the inner ear and cause noise-induced hearing loss (NIHL).
With intense exposures (>/= 140 dB SPL), a portion of the organ of Corti is displaced from its position on the basilar membrane and is often found floating within scala media. Swollen hair cells are found at the edges of the lesion and signs of damage are apparent in the nonmyelinated nerve fibers of the organ of Corti both within and adjacent to the displaced portion.
With moderate-level exposures for long durations such as those found in noisy industries (i.e., </= 90 dB SPL), a few scattered sensory (i.e., hair) cells probably degenerate within the organ of Corti during each day of work. In general, the noise-induced loss of hair cells is very gradual. The amount of structural damage which is present in a given ear depends on its auditory history. The longer the exposure, the greater the number of missing sensory cells.
Hence, the part of the ear is damaged most easily by continued exposure to loud noise is hair cells.