An aqueous solution of sodium stearate, ${\mathrm{C}}_{17}{\mathrm{H}}_{35} \mathrm{COONa}$, becomes a colloidal sol at the concentration of $1.2 \times 10–3 \mathrm{M} \mathrm{at} 25°\mathrm{C}$. If at this concentration, $2.4 \times {10}^{13}$ colloidal (micelle) particles are present per ${\mathrm{mm}}^3$ , the number of stearate ions in each colloidal particle is : $(\mathrm{NA} = 6 \times {10}^{23})$