Ans: Quantum mechanics allows the calculation of properties and behaviour of physical systems. it's typically applied to microscopic systems: molecules, atoms, and sub-atomic particles. Its application to larger and more complex systems raises technical and philosophical questions, although there seems to be no upper limit to its range of validity. Predictions of quantum physics are verified experimentally to a particularly high degree of accuracy. A fundamental feature of the thought is that it always cannot predict with certainty what's getting to happen, but only give probabilities.