Question

19. H2O, CO2, CaCl2, and Na2CO3 (the numbers are subscripts) are all examples of that tell which atoms and how much of each atom is needed to make a molecule of a substance.

A.chemical formulas
B.types of atoms
C.elements​

Answer 1

A. Chemical formulas

Step-by-step explanation:

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In this case, since chemical formulas are written or drawn representations of what atoms and how much of them are present in a molecule, which is composed by two or more different atoms, we can infer that molecules such as H2O (water), CO2 (carbon dioxide), CaCl2 (calcium chloride) and Na2CO3 (sodium carbonate) are given as a. Chemical formulas, because we can see there are two hydrogens and one oxygen in water, one carbon and two oxygens in carbon dioxide, one calcium and two chlorines in calcium chloride and two sodiums, one carbon and three oxygens in sodium carbonate.

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