What are the values of Wien's constant in $SI$ and $CGS$ units?

Solar radiation emitted by the Sun resembles that of a black body at a temperature of $6000 \, K$. The maximum intensity of radiation is emitted at a wavelength of $4800 \, \mathring{A}$. If the temperature of the Sun decreases from $6000 \, K$ to $3000 \, K$,then at what wavelength (in $\mathring{A}$) will the maximum intensity of radiation be emitted?

Which of the following is the $\nu_m - T$ graph for a perfectly black body? ($\nu_m$ = maximum frequency of radiation,$T$ = absolute temperature)

The surface temperature of the sun which has maximum energy emission at $500 \,nm$ is $6000 \,K$. The temperature of a star which has maximum energy emission at $400 \,nm$ will be: (in $\,K$)

$A$ black body has a maximum wavelength of $\lambda_m$ at a temperature of $2000 \ K$. What will be the maximum wavelength at a temperature of $3000 \ K$?

The wavelength of the radiation emitted by a black body is $6 \ mm$ and Wien's constant is $3 \times 10^{-3} \ mK$. Then the temperature of the black body is (in $K$)