To determine which compound, calcium hydroxide (Ca(OH)2) or potassium phosphate (K3PO4), has more atoms, we need to calculate the total number of atoms in each compound.

Calcium hydroxide (Ca(OH)2):

1 Calcium atom (Ca)

2 Oxygen atoms (O)

2 Hydrogen atoms (H)

Total number of atoms in Ca(OH)2: 1 + 2 + 2 = 5 atoms

Potassium phosphate (K3PO4):

3 Potassium atoms (K)

1 Phosphorus atom (P)

4 Oxygen atoms (O)

Total number of atoms in K3PO4: 3 + 1 + 4 = 8 atoms

Therefore, potassium phosphate (K3PO4) has more atoms than calcium hydroxide (Ca(OH)2).