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A. when evaluating a source for reliability, if they are talking about a product from a company that sponsors them they may not be honest, or if they are sponsored by a reliable company they can be trusted it depends what way you look at it.
The two substances are rock (molten and solid) and metal (solid + liquid).
Layers of the earth from the outside in:
1. crust. hard rock/dirt/ground. Shell
2. mantle. melted rock and stuff. Egg white
3. core. Outer core - liquid. Inner core- solid. Nickle and iron. Yolk
The primary role of hydrochloric acid is to sterilize the food you eat and to prevent harmful bacteria from entering the GI tract. HCL also triggers the release of enzymes such as pepsin which are essential for the digestion of protein.
Interaction between two species as both attempt to use the same environmental resources is
Species