These encompass thermodynamics, governing energy transfer and chemical reactions; transport phenomena, analyzing momentum, heat, and mass transfer; reaction engineering, studying kinetics and reactor design; and process control, managing system dynamics and optimization. Additionally, materials science theories inform the selection and behavior of materials in chemical processes. Environmental engineering theories address pollution prevention and sustainability. How do these theories collectively shape the modern practice of chemical engineering, and what challenges do they address in industries ranging from pharmaceuticals to petrochemicals and beyond?