Continuation of Quantum Mechanics I (Introduction to Quantum Mechanics and Quantum Mechanics in One-dimension) including study of symmetries and perturbation theory. Applications to orbital angular momentum, spherical symmetric potentials (three-dimension square well potential, hydrogen like atom, three-dimension harmonic oscillator etc.), spin angular momentum, spin-orbit interaction and composition of angular momentum. A concept of symmetries is characterized by orbital angular momentum, spin angular momentum and interchange of the two particles. Perturbation theory provides specific approach to the calculation, and students should be able to understand when a quantum mechanics approach to a problem may be advantageous and necessary. Topics include time-independent/ time-dependent perturbation theory, transition probability, and variation method. The discussion continues in Quantum Mechanics III (scattering, many-electron problems, interaction of electric field and electrons).