KS3 General Knowledge Practice Test 2026 – Comprehensive Exam Prep

The chemical formula for glucose is C6H12O6. This formula represents a molecule consisting of six carbon atoms (C), twelve hydrogen atoms (H), and six oxygen atoms (O). Glucose is a simple sugar and is one of the most important carbohydrates; it serves as a primary source of energy for many living organisms.

The structure of glucose indicates that it is a monosaccharide, which means it is a single sugar unit. The composition given in the formula directly reflects the molecular structure of glucose, which can be represented in various forms such as a linear chain or a cyclic ring form.

Other chemical formulas listed correspond to different substances: CO2 represents carbon dioxide, which consists of one carbon atom and two oxygen atoms and is critical in processes such as respiration and photosynthesis. C12H22O11 is the formula for sucrose, which is a disaccharide made of two monosaccharides (glucose and fructose). Meanwhile, C3H6O3 is the formula for lactic acid, which is produced during anaerobic respiration in muscle cells. Each of these compounds serves different roles in chemistry and biology, but only C6H12O6 corresponds to glucose.