Find the de-Broglie wavelength of a neutron , in thermal equilibrium with matter, having an average kinetic energy of $ \large\frac{3}{2}$$kT$ at $300k$ .given : $h= 6.63 \times 10^{-34}\;Js,m_n= 1.675 \times 10^{-27}\;kg; k= 1.8 \times 10^{-23}JK^{-1}$

Question

$\begin{array}{1 1} 1.45 \times 10^{10}\;m \\1.45 \times 10^{-10}\;m \\ 1.45 \times 10^{26}\;m \\ 1.45 \times 10^{-20}\;m \end{array} $