$f(E_C)=\dfrac{1}{1+exp\left[\dfrac{(E_C-E_V )}{KT}\right]}$

We know that,

K = Boltzman constant = 1.38×10-23 J/K

Boltzman constant can be expressed in eV as:

$K=\dfrac{1.38\times10^{-23}}{1.6\times10^{-19}}=86.25\times10^{-6}eV$

Also for an intrinsic semiconductor

$E_C-E_V=\dfrac{E_g}{2}$

$E_C-E_V=\dfrac{1.12}{2}=0.56 eV$

$f(E_C )=\dfrac{1}{1+exp\left[\dfrac{0.56}{86.25\times10^{-6}\times(20+273)}\right]}=\dfrac{1}{1+exp\dfrac{0.56}{22.15956}}$

(∴f(E_C )=\dfrac{1}{1+e^{0.0253} }=0.4936)