Which is the only source of sound that produces pure notes?

A long flexible spring is called

Which quantity out of the following determines the loudness of a sound wave?

Sound waves cannot pass through

Supersonic means

The distance between two consecutive crests is L, then the wavelength is given by

A wave completes 20 vibrations in 2.5 s, its frequency is

The quantity of intensity of sound wave is

A wire stretched between two fixed supports, is plucked exactly in the middle and then released. It executes

Waves transfer 'X' from one place to another. Here 'X' refers to