Answer:
Pure elements:
Hydrogen(H)
Nitrogen(N)
Magnesium (Mg)
Pure Compounds:
Oxygen gas(O2)
Water (H2O)
Ammonia (NH3)
Explanation:
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Molecules are pure substances. This is because a molecule has a set ratio of elements in order to make that compound have the same properties.
For example:
Water is H₂O. Always. There is no alternate water formula.
Sand however, is a mixture, who knows exactly what is in sand, and how much of it is in there.
A is incorrect because, the carbon dioxide is being pushed up by the below mixture of baking soda and vinegar.
B is incorrect because the carbon dioxide gets pushed out of the bottle and joins the air around the bottle, adding carbon dioxide to the air around the bottle.
C is incorrect because the mass of the reactants, the baking soda and vinegar, is more then the carbon dioxide it creates.
D is correct because the mass of the reactants is more then the carbon dioxide it creates.
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