When red light $($monochromatic and coherent$)$ illuminates a grating with $7000$ lines per centimeter, its second maximum $($bright$)$ is observed at $62\mathrm{.}4$ from the central bright on a screen that is placed $1\mathrm{.}2$ m away from the grating.

A$.$ To observe a maximum or bright fringe, the path length difference must be

B$.$ The slit separation for the grating, $d=m.$

C$.$ The wavelength of the light used for forming this pattern is nm$.$

$q,$

D$.$ If the grating is replaced by a double slit now with the slit separation of $25m$ and a green laser of $=523$ nm is used, then

I. the second bright fringe will form a $$ degrees.

II$.$ The linear distance of the third dark band from the central bright is

$$ cm $.$ III The linear separation between the second bright and the third dark band will be