Q. Illustrate the Quantum Mechanics?

Ans: In 1924, a French scientist named Louis de Broglie proposed another model for the nature of the electrons in atoms. He predicted that, instead of being considered a discrete particle, an electron can also be thought of as a wave. Several scientists tested de Broglie's hypothesis, and were able to show that a beam of electrons does indeed have wave-like properties.

If an electron behaves like a wave, instead of a simple discrete particle, how can it's location around the nucleus be determined at any given instant?

This is where the branch of science known as quantum mechanics comes in handy! Quantum mechanics describes the motion of small particles, such an electrons, that are confined to a limited area of space.