Answer:
a. Chemical formula
Step-by-step explanation:
A notation that shows which elements, and how many of each type a compound contains is a chemical formula.
Basically, a chemical formula helps scientists to show or illustrate the type and number of atoms present in a particular molecule or compound by using numerical subscript, ions and atomic symbol of a chemical element.
This ultimately implies that, a chemical formula is used to describe or denote the exact amount of atoms that make up a molecule or compound.
Some examples of a chemical formula are;
Water =
![H_(2)O](https://img.qammunity.org/2021/formulas/chemistry/college/gfp18bjqx6lwmwbidodhakbmvhplzvjlip.png)
Sodium Hydroxide =
![NaOH](https://img.qammunity.org/2021/formulas/chemistry/college/u9l80o5dbp5uyzi3zvrem9p1bp4fmg46h9.png)
Hydrochloric acid =
![HCl](https://img.qammunity.org/2021/formulas/chemistry/college/bxkco0ucp6ood4hi1vp9fi6l5q01deg91g.png)
Carbon II oxide =
![CO_(2)](https://img.qammunity.org/2021/formulas/chemistry/college/4yn94gg4m6czhz30gvtcas6o8qudbir04f.png)