Limit of resolution of a telescope is given by, 

${\vartheta }_{\min }=\frac{1.22\lambda }{a}$, where $\lambda$ is the wavelength of the light and $a$ is the aperture diameter.

Given, $\lambda =600 \mathrm{nm} \text{and} a=2 \mathrm{m}$

${\vartheta }_{\min }=\frac{1.22\times 6\times {10}^{-7}}{2}$

$\Rightarrow {\vartheta }_{\min }=3.66\times {10}^{-7} \mathrm{rad}$