What equipment consists of a bowl and a stick used for grinding substances?

The equipment that consists of a bowl and a stick used for grinding substances is known as a pestle and mortar. The mortar is the bowl, typically made of materials like ceramic, stone, or glass, while the pestle is the stick used to crush and grind solid substances into a powder. This tool is commonly used in laboratories and kitchens to prepare samples for various experiments or culinary applications by breaking down solid materials and mixing them effectively.

Other options listed serve different purposes: a beaker is used for mixing and heating liquids; an Erlenmeyer flask is designed for mixing solutions and has a narrow neck to prevent spillage; and an eyedropper is a tool for transferring small amounts of liquid. Each of these has its specific applications, but none fulfill the function of grinding substances like a pestle and mortar does.