An evidence of the wave nature of matter is

Step 1: Analyze the question The question asks for evidence that matter (such as electrons) behaves like a wave. This is the de Broglie hypothesis: moving particles have an associated wavelength, λ = h/(mv) = h/p.

Step 2: Concept Only waves show interference and diffraction. So if a beam of particles, like electrons, produces a diffraction pattern, that is direct evidence of the wave nature of matter. Davisson and Germer demonstrated this in 1927 when they diffracted electrons off a nickel crystal.

Step 3: Check each option

• A. Brownian motion: Random movement of small particles in a fluid, caused by molecular collisions. It is evidence for the particle (kinetic) nature of matter, not waves.
• B. Compton effect: X-ray photons scatter off electrons and lose energy. It shows the particle nature of light (photons), not the wave nature of matter.
• C. Diffraction: Electron diffraction shows that matter behaves as a wave. ✔
• D. Diffusion: Spreading of particles from high to low concentration. It is a molecular process and says nothing about waves.
• E. Photoelectricity: Light ejects electrons from a metal surface. It shows the particle nature of light (photons).

Step 4: Answer The correct answer is **C.

Exam tip: Remember the pairing:

• Diffraction and interference → wave nature (of light, or of matter such as electrons)
• Photoelectric and Compton effects → particle nature of light

If the question says "wave nature of matter," think "electron diffraction."