Question

how blood is a heterogeneous substance?​

Answer 1

A heterogeneous mixture is made of different substances that remain physically separate. Heterogeneous mixtures always have more than one phase (regions with uniform composition and properties).

Blood is a heterogeneous mixture because the blood cells are physically separate from the blood plasma. The cells have different properties than the plasma. The cells can be separated from the plasma by centrifuging, which is a physical change.