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# The coagulating power of an electrolyte for arsenious sulphide sol decreases in the order:

(a) $Na^+ > Al^{3+} > Ba^{2+}$
(b) $PO^{3-}_4 > SO^{2-}_4 > Cl^-$
(c) $Cl^- > SO^{2-}_4 > PO^{3-}_4$
(d) $Al^{3+} > Ba^{2+} > Na^+$

Answer: $Al^{3+} > Ba^{2+} > Na^+$
$As_2S_3$ ia a negative sol and therfore coagulating power decreases as $Al^{3+} > Ba^{2+} > Na^+$ .