What is carbon that is not combined with hydrogen called?

Fixed carbon refers to carbon that is not combined with hydrogen and is typically found in solid forms, such as coal, graphite, or char. This form of carbon is part of the structural framework of various carbon-based materials and is important in industrial processes like combustion, where it serves as a source of energy. In contrast to other forms of carbon that may be volatile or reactive when combined with hydrogen, fixed carbon is stable and plays a crucial role in the thermodynamic properties of materials and their applications. Understanding fixed carbon is fundamental in fields like materials science, chemistry, and energy production.