Describes mathematically the wave properties of electrons and other very small particles?

• A. Orbital
• B. Line-emission spectrum
• C. Quantum theory
• D. Principle quantum number

Answer: (C)

Quantum theory describes how electrons and other very small particles exhibit wave-like behavior in a precise, mathematical way. It introduces wavefunctions that encode the probability of finding a particle in a given region and uses equations like the Schrödinger equation to predict how these probabilities evolve. The wave nature is linked to momentum through the de Broglie relation and leads to familiar features like interference and quantized energy levels, all within a single formal framework. The other terms describe parts of that framework or phenomena derived from it but do not themselves provide the mathematical description of wave properties: an orbital is a region defined by the probability density, a line-emission spectrum arises from transitions between energy levels, and the principal quantum number labels those energy levels.