You will be given a definition of a task first, then some input of the task.
Given a scientific passage and an answer, generate a question for the given answer.

Passage: An alloy is a mixture composed of two or more elements, at least one of which is a metal. You are probably familiar with some alloys such as brass and bronze. Brass is an alloy of copper and zinc. Bronze is an alloy of copper and tin. Alloys are commonly used in manufactured items because the properties of these metal mixtures are often superior to a pure metal. Bronze is harder than copper and more easily cast. Brass is very malleable and its acoustic properties make it useful for musical instruments. Answer: alloy
Output:
Brass and bronze are examples of what type of mixture composed of two or more elements, at least one of which is a metal?