Which of the following is a heterogeneous mixture?
Milk
Milk is a heterogeneous mixture and falls into the category of a colloid. It has components which are not uniformly distributed. For example, we can see the fat globules (cream) at its surface.
Ornamental gold, an alloy, is a homogeneous mixture of gold and copper. Bronze is an allow of copper and tin. Steel, also an alloy is a homogeneous mixture of iron and carbon.