Moles and particles are related through Avogadro's number, which states that one mole of any substance contains 6.022 x 10^23 particles (atoms, molecules, or ions).
To find the number of particles in 4 moles of a substance, you would multiply the number of moles by Avogadro's number:
Number of particles = 4 moles * 6.022 x 10^23 particles/mole
The result would give you the total number of particles in 4 moles of the substance.