Answer
The separation will remain the same.
Work Step by Step
This is a diffraction grating, so we can look at equation (36-30) to see how the separation of the lines, $\Delta \theta$, is affected by increasing the amount of slits, N. Therefore;
$$\frac{\Delta \theta}{\Delta \lambda}=\frac{m}{d\cos \theta}$$
We can see that increasing the amount of slits, N, will does not affect the separation of the lines or the change in wavelength, $\Delta \lambda$ , or the order, m.
