Who found out about dual behavior of a matter? 

de Broglie

The correct correct answer is option 1. de Broglie.

Louis de Broglie, a French physicist, proposed the theory of wave-particle duality in 1924. This theory suggests that particles, such as electrons, exhibit both wave-like and particle-like properties. De Broglie's idea was a significant development in the understanding of the nature of matter and contributed to the foundation of quantum mechanics.

Key points about de Broglie's wave-particle duality:

1. Wave-Particle Nature: De Broglie proposed that particles, such as electrons, have both wave and particle characteristics. The wavelength (λ) associated with a particle is inversely proportional to its momentum (p), according to the de Broglie equation: λ = h / p, where h is Planck's constant.

2. Confirmation by Experiments: The wave-particle duality was experimentally confirmed through various experiments, particularly the famous Davisson-Germer experiment in 1927. This experiment demonstrated the diffraction of electrons, a phenomenon typical of waves, when they interacted with a crystal lattice.

3. Quantum Mechanics:  de Broglie's ideas were incorporated into the emerging field of quantum mechanics, which was further developed by other physicists such as Erwin Schrödinger, Werner Heisenberg, and Max Born. Quantum mechanics provides a comprehensive framework for understanding the behavior of particles at the atomic and subatomic levels.

de Broglie's wave-particle duality laid the groundwork for a more complete and accurate description of the behavior of particles in the quantum realm, challenging classical notions of particles strictly behaving as classical particles or waves.