Answer:
5 orders.
Explanation:
The condition for diffraction maxima,
[tex]sin \theta = mN\lambda\\m=\frac{sin \theta}{N\lambda}[/tex]
[tex]m=\frac{sin 90^{\circ}}{(380\frac{lines}{mm}(\frac{1000mm}{1m} )) 457\times 10^{-9} m }\\m=5.75\simeq5[/tex]
So maximum m is 5 which means it produce 5 orders.
Therefore, the number of possible order will produce by visible light of wavelength 457 nm is 5 orders.
