Which of the following is not a homogeneous mixtures?
Milk
Definition for homogeneous substance.
A mixture having a uniform distribution of its constituent particles is called homogenous mixtures.
Definition for heterogeneous mixtures.
A mixture has a non-uniform concentration through the mixtures.
Explanation for correct.
(B)-Milk
Milk is a heterogeneous mixture. Milk actually appears homogeneous but it is a heterogeneous mixture in which the particles are insoluble and not evenly distributed.
Explanation for incorrect options.
(A)-Steel,(C)-Brass,(D)-Bronze.
These are homogeneous mixtures.
Therefore option(B) is the correct answer.