Which one of the following mixtures is homogeneous?

A homogeneous mixture is one where the components are evenly distributed and cannot be distinguished even under a microscope [c1]. Such mixtures are uniform in nature and are often referred to as solutions [t3]. Methanol and water are both polar liquids that are completely miscible, forming a single-phase liquid solution with a uniform composition throughout [t6]. In contrast, starch and sugar (solid-solid), graphite and charcoal (solid-solid), and calcium carbonate and calcium bicarbonate (solid-solid) are heterogeneous mixtures. These components do not mix at the molecular level in their solid states and remain as distinct phases with non-uniform distributions [c1][c3]. While calcium carbonate is largely insoluble in water, forming a suspension (heterogeneous), methanol and water intimately combine to be observed as a single substance [t3][t4].

Sources

1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > 8.1 What Are Mixtures? > p. 117
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 9: The Amazing World of Solutes, Solvents, and Solutions > Probe and ponder > p. 135