There are 5.4 × 10^23 atoms in 12 g NaOH .
Step 1. Convert grams of NaOH to moles of NaOH
Moles of NaOH = 12 g NaOH × (1 mol NaOH /40.00 g NaOH)
= 0.300 mol NaOH
Step 2. Convert moles of NaOH to formula units (FU) of NaOH
FU of NaOH = 0.300 mol NaOH × (6.022 × 10^23 Fu NaOH/1 mol NaOH)
= 1.81 × 10^23 FU NaOH
Step 3. Convert FU of NaOH to atoms
1.81 × 10^23 FU NaOH × (3 atoms/1 FU NaOH) = 5.4 × 10^23 atoms