Lactose in milk exists in the form of

Lactose in milk exists in the form of Solution.
Lactose is dissolved in the serum (whey) phase of fluid milk. It is dissolved in solution and is found in 2 forms, called the α-anomer and ß-anomer, that can convert back and forth between each other.
Lactose in milk is present in form of true solution and milk fat as an emulsion whereas milk proteins are dispersed as a colloid.