This book is intended to those who want to strengthen their knowledge in nuclear physics, it contains many different solved problems in many subjects in introductory nuclear physics, the problems in the book are solved by following step by step approach and by including all the details of derivations and computations when needed. The book is very helpful to students who are in need of explanations of difficult problems in a step by step solving techniques, even if the problem is difficult to understand, the student will find it easy when studying from the book. The book includes many subjects of special interest to students specializing in nuclear physics or in nuclear engineering. The subjects of the solved problems are on the following : nuclear force, range of the nuclear force, nuclear charge density, Q-value, binding energies of nuclei, complete derivation of Rutherford scattering formula, the semi-empirical mass formula, alpha decay, Gamow theory of alpha decay, beta decay, radioactivity and radioactive equilibrium, shell-model with necessary derivations of energy levels in the harmonic oscillator model, Quantum Scattering, Breit-Wigner Formula derivation, neutron proton scattering, calculation of the potential depth of the deutron, fission, fissility condition and the critical mass calculations in nuclear fission explosions. The book can also be used as a reference to the instructor of the course where there are many interesting problems where the instructor may choose to be included in his or her exams, the book also is very helpful to those students who are willing to pass the PhD preliminary qualifying exam.