For a given single slit, the diffraction pattern is obtained on a fixed screen, first by using red light and then with blue light In which case, will the central maxima, in the observed diffraction pattern, have a larger angular width ?
Angular width of central maxima is
$\theta $ = $\lambda $/a
Clearly, $\theta $ isproprtionalto X
The wavelength of red colour is greater than that of blue colour. So, the angular width of red colour is large.