The coagulating power of an electrolyte is a measure of its ability to cause the coagulation or precipitation of a colloidal solution.

$\mathrm{Coagulation} \mathrm{power} \mathrm{\alpha }\frac{1}{\mathrm{Coagulation} \mathrm{value}}$

 Coagulating value of ${\mathrm{AlCl}}_3$ for ${\mathrm{As}}_2 {\mathrm{S}}_3=0.09$
 Coagulating value of $\mathrm{NaCl}$ for ${\mathrm{As}}_2 {\mathrm{S}}_3=50.04$

Then,

$$\begin{gathered} \frac{(\mathrm{C}.\mathrm{V}{)}_{{\mathrm{AlCl}}_3}}{ (\mathrm{C}.\mathrm{V}{)}_{\mathrm{NaCl}}} =\frac{(\mathrm{C}.\mathrm{P}{)}_{\mathrm{NaCl}}}{ (\mathrm{C}.\mathrm{P}{)}_{{\mathrm{AlCl}}_3}} \\ \frac{0.09}{50.04}=\frac{(\mathrm{C}.\mathrm{P}{)}_{\mathrm{NaCl}}}{ (\mathrm{C}.\mathrm{P}{)}_{{\mathrm{AlCl}}_3}} \\ (\mathrm{C}.\mathrm{P}{)}_{{\mathrm{AlCl}}_3}=556(\mathrm{C}.\mathrm{P}{)}_{\mathrm{NaCl}} \end{gathered}$$
  So the answer is $556.$