Answer:
The wavelength of the light is 562.5 nm
Solution:
As per the question:
Order, n = 1
Slit separation, d =

Distance from the bright fringe, y = 0.18 m
Distance between the screen and the grating, D = 0.8 m
Now,
We know from the eqn for diffraction:

n = 1
(1)
Also,
For very small angle,
:
≈

Using the above value in eqn (1):
