This is the correct option. If the vocal cords are loose and thick, a sound of low frequency is produced.

This is the correct option, as all the above given options show that sound is produced by vibrating objects.

This is the correct option, as vacuum is the medium where sound cannot travel because vacuum has no molecules that can vibrate and carry sound waves.

This is the correct option, as this statement is false. Sound of a radio speaker is not produced due to the vibrating air columns of the speaker. It is due to the vibrations of the cone of speaker.

This is the correct option. An example of sound produced by vibrating air column is the flute. An example of sound produced by vibrating membranes is the tabla. An example of sound produced by vibrating plates is the bicycle bell.

This is the correct option. Sound waves need a medium to travel. As there is no air on moon, there is no medium for air waves to travel. Thus, sound cannot be heard on the surface of moon. 

Cochlea is the spiral cavity of the inner ear containing the organ of Corti, which produces nerve impulses in response to sound vibrations. It is a part of the inner ear, and not middle ear.

This is the correct option. Decibel is the unit of loudness of sound.

This is the correct option. Amplitude of vibrations is the maximum displacement of a vibrating object from its central position. Time-period of vibrations is the time taken by a vibrating object to complete one vibration. Frequency of vibrations is the number of vibrations made in one second.

This is the correct option as all the statements are correct statements. The vocal cords are attached to the muscles, which change the tension in the cords and the distance between the cords. The lungs pass a current of air between the two vocal cords, which causes them to vibrate and make sound. The larynx is situated in our throat at the top of the trachea.

This is the correct answer option as this is an incorrect statement. Three tiny bones in the middle part of the ear act as a system of levers and amplify sound vibrations coming from the ear drum, and not cochlea.

This is the correct option as this is a false statement. Human beings produce sound by using the voice box which is called the 'larynx', and not the 'cochlea'.

This is a false statement. Thus, it is a correct option. The time-period of a pendulum depends only on the length of the pendulum and not on the amplitude of vibrations.

This is the correct option. Due to its very high frequency, ultrasound has a greater penetrating power than ordinary sound.

This is the correct option. Sounds produced by different singers or different musical instruments can be distinguished on the basis of a characteristic of sound called timbre. Timbre of sound is the combination of qualities of a sound that distinguishes it from other sounds with same pitch and volume.

This is the correct option. The range of audible frequencies of sound of human hearing is from 20 - 20,000 hertz.

This is the correct option, as the statement is false. The loudness of sound is directly proportional to the square of amplitude of vibrations of the sound producing object. If the amplitude of vibrations is doubled. then the loudness will become four times and if the amplitude of vibrations is halved, then the loudness will become one-fourth. 

This is the correct option. Violin is a stringed musical instrument. Cymbals are a plate type musical instrument. Trumpet is a wind type musical instrument.

This is the correct option, as all of the above are the uses of ultrasonic waves. 

This is the correct option. The frequency range of sound that can be produced by a vibrating simple pendulum is 0 - 20 Hz.