For a double slit experiment, what is the smallest separation (in nm) between two slits that will produce a second-order maximum for 754 nm visible light

The answer is trial 3.

Iassume the answer is 75 feet. inwards to outwards rather than outwards to inwards. probably be 75.hachures are stokes drawn in direction of the steepest slope. a series of short parallel lines drawn on a map to indicate topographic relief. it is actually called hachures on contour lines. the small marks in the center of the feature are called hachures.observe the picture attached