Here's how to determine the number of atoms in C₆H₁₂O₂ (glucose):

* Count the subscripts: The subscripts tell you how many of each type of atom are present in one molecule.

* C (Carbon): 6 atoms

* H (Hydrogen): 12 atoms

* O (Oxygen): 2 atoms

* Total: 6 + 12 + 2 = 20 atoms

Therefore, there are 20 atoms in one molecule of C₆H₁₂O₂ (glucose).