Question

What is the wavelength of a sound wave with a frequency of 784 hz, corresponding to the note g5 on a piano?

Answer 1

the speed of light in air  is =343 m/s
frequency of note g  = 748 hz

In order to calculate the wavelength it is related by the following formula

λ=c/v

where c is the speed of light in air 
  v is the frequency.

=343/748
=0.458 m
 the unit is meters