How do you know how many valence electrons an atom has?

Acertain sound is recorded by a microphone. the same microphone then detects a second sound, which is identical to the first one except that the amplitude of the pressure fluctuations is larger. in addition to the larger amplitude, what distinguishes the second sound from the first one? it is perceived as higher in pitch. it is perceived as louder. it has a higher frequency. it has a longer wavelength.