To determine the number of atoms in 18 grams of glucose (C6H12O6), we need to calculate the number of moles of glucose present and then multiply by Avogadro's number (6.022 x 10^23 atoms per mole).

Step 1: Calculate the number of moles of glucose

The molar mass of glucose (C6H12O6) is:

(6 x 12.01 g/mol for carbon) + (12 x 1.008 g/mol for hydrogen) + (6 x 16.00 g/mol for oxygen)

= 180.156 g/mol

The number of moles of glucose in 18 grams is:

18 g / 180.156 g/mol = 0.1 moles

Step 2: Multiply by Avogadro's number

The number of atoms in 0.1 moles of glucose is:

0.1 moles x 6.022 x 10^23 atoms/mole = 6.022 x 10^22 atoms

Therefore, 18 grams of glucose contains 6.022 x 10^22 atoms.