What are the conditions of Fresnel and Fraunhofer diffraction?

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : An electron microscope can achieve better resolving power than an optical microscope.

Reason R : The de Broglie's wavelength of the electrons emitted from an electron gun is much less than wavelength of visible light.

In the light of the above statements, choose the correct answer from the options given below:

Two towers on top of two hills are $60 \mathrm{km}$ apart. The line joining them passes $100 \mathrm{m}$ above a hill halfway between the towers. The longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction effects is

In Fresnel's experiment, the width of the fringe depends upon the distance 

Represent the union of two sets by Venn diagram for each of the following.

$X=\{x | x$ is a prime number between $80$ and $100\}$

$Y=\{y | y$ is an odd number between $90$ and $100\}$

In single slit diffraction pattern, central maxima is brighter than the successive maxima on either side while in interference all the maxima are equally bright. Explain.