Answer
wavelength = 10622.71 nm , frequency = 2.82$\times10^{13} hertz$
Work Step by Step
Temperature of Blackbody T = 0 $^{0}C$
Temperature of blackbody in absolute kelvin scale T = temperature in $^{0}C$ + 273
Temperature of blackbody in absolute kelvin scale T = 0 $^{0}C$ + 273
Temperature of blackbody in absolute kelvin scale T = 273 K
From Wiens displacement law $\lambda_{max} T = 2.90\times10^{-3} m.K$
$\lambda_{max} = \frac{2.90\times10^{-3} m.K}{T}$
$\lambda_{max} = \frac{2.90\times10^{-3} m.K}{273 K}$
$\lambda_{max} = 0.01062271\times10^{-3}$ m
$\lambda_{max} = 10622.71\times10^{-9}$ m
$\lambda_{max}$=10622.71 nm
since frequency $ f= \frac{c}{\lambda}$ where c is speed of light
$ c= 3\times10^{8}$m/s
so $ f= \frac{3\times10^{8}m/s}{10622.71\times10^{-9} m}$
$ f= 2.824138\times10^{13}/s$
$ f= 2.824138\times10^{13} hertz$