What is the angular separation between two lines of $\lambda_1 =5882 \mathring{A}$ and $\lambda_2 =5852 \mathring{A}$ in first order grating with 6000 lines per cm in normal incidence.

Question

$(a)\;2.5 \times 10^{-3}\;rad \\ (b)\;1.8 \times 10^{-3}\;rad \\ (c)\;3.6 \times 10^{-3}\;rad \\ (d)\;1.8 \times 10^{-4}\;rad $