Due to which optical phenomenon do we not see the shadow of an opaque object clearly?

Consider the diffraction pattern obtained from the sunlight incident on a pinhole of diameter $0.1 \, \mu m$. If the diameter of the pinhole is slightly increased,it will affect the diffraction pattern such that :

How will the diffraction pattern change when yellow light is replaced by blue light? The fringe will be :-

$A$ single slit of width $d$ is illuminated by violet light of wavelength $400 \ nm$ and the width of the diffraction pattern is measured as $Y$. When half of the slit width is covered and illuminated by yellow light of wavelength $600 \ nm$,the width of the diffraction pattern is

$A$ screen is placed at a certain distance from a narrow slit,which is illuminated by a parallel beam of monochromatic light. What will you observe if you scan the screen with the help of a microscope?

Light of wavelength $5000 \, \mathring{A}$ is incident on a single slit such that the first minima is formed at a distance $5 \, mm$ from the centre. If the screen is placed $2 \, m$ away,then find the width of the slit in $mm$.