This post provides the complete answer key along with detailed explanations for the Modern Physics exercise of 50 MCQs, designed according to the PMDC syllabus for MDCAT and NUMS aspirants. The questions reflect the pattern of MDCAT and NUMS past papers, covering essential topics such as photoelectric effect, wave-particle duality, atomic models, and the theory of relativity. These explanations offer clarity and insight, helping students from UHS, DUHS, KMU, SZABMU, BOLAN, and JSMU strengthen their preparation for medical entrance exams.