In the context of blood composition, what kind of mixture is blood?

• A. An emulsion of two immiscible liquids
• B. A pure substance (single compound)
• C. A homogeneous mixture (a true solution)
• D. A heterogeneous mixture (a suspension of formed elements in plasma)

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the components of blood. Blood consists of plasma (a liquid) and formed elements such as red blood cells, white blood cells, and platelets.
2. Step 2: Recognize that plasma is mostly water with dissolved substances, making it a homogeneous liquid, but the formed elements are solid particles suspended in this liquid.
3. Step 3: Define the types of mixtures: a homogeneous mixture (true solution) has uniform composition throughout, while a heterogeneous mixture contains visibly different components or phases.
4. Step 4: Since blood contains solid cells suspended in liquid plasma, it is not a true solution or an emulsion of two immiscible liquids, but rather a suspension where particles are dispersed but not dissolved.
5. Step 5: Conclude that blood is a heterogeneous mixture, specifically a suspension of formed elements in plasma, because the cells can be separated by centrifugation and are not uniformly dissolved.