<span>Unidirectional flow in the heart is ensured because the heart contains valves that prevent backflow.
These valves keep the flow of the heart going in one direction (hence the name "unidirectional").</span>
Answer:
The answer is C) osteopenic
Answer:
a glass of muddy water
Explanation:
Pure substances contain only one element or compound.
Calcium is one element so it is a pure substance. Ice and water have the same molecular structure, so it is a pure substance. Aluminum oxide is a chemically pure compound.
The only example that is not a pure substance is muddy water due to the multiple components of mud mixing with the components of water.
Hope that helps.
C
hope this helps u to understand.
