No, brass is not a pure substance; it is an alloy. Brass is primarily made up of copper and zinc, although it can also contain small amounts of other metals such as lead to improve its machinability. The specific proportions of copper and zinc can vary, leading to different types of brass with varying properties.
In chemistry, a pure substance consists of a single type of particle and has a uniform and consistent composition. Since brass is composed of two or more different elements (copper and zinc), it does not meet this definition. Therefore, while brass is a valuable material with useful properties, it is classified as an alloy rather than a pure substance.