Final answer:
In single-chain silicates, silica tetrahedra share two oxygens, which allows them to link together and form long chains with a silicon-to-oxygen ratio of 1 to 3 (SiO3).
Step-by-step explanation:
In single-chain silicates, silica tetrahedra share two oxygens. Each silica tetrahedron consists of a silicon atom surrounded by four oxygen atoms, forming a structure known as a tetrahedron. Silicates are a varied group of minerals that all contain silicon-oxygen bonds with silicate tetrahedra connected in different forms, including rings, sheets, or three-dimensional networks. When these tetrahedra link together to form a single chain, they do so by sharing oxygen atoms at their adjoining corners. For long chains, this sharing results in a silicon-to-oxygen ratio of 1 to 3 (SiO3).