A screen is placed 50 cm from a single slit which is illuminated with $6000 ^{\circ}$ light . If the distance between the first and third minima in the diffraction pattern is $3.00\;nm$ , what is the width of the slit ?

Question

$\begin{array}{1 1} 0.2\;mm \\ 0.2\;cm \\ 2\;mm \\ 2\;cm \end{array}$