Answer
(a) $0.807m$
(b) decrease
(c) $0.722m$
Work Step by Step
(a) We can find the wavelength as
$\lambda=\frac{v}{f}$
We plug in the known values to obtain:
$\lambda=\frac{343}{425}=0.807m$
(b) We know that the frequency and wavelength are inversely proportional. Thus, if the frequency is increased then the wavelength will decrease.
(c) The wavelength can be calculated as
$\lambda=\frac{v}{f}$
$\implies \lambda=\frac{343}{465}=0.722m$
