Question

The coagulating power of electrolytes having ions $N{a}^{+},A{l}^{3+}$ and $B{a}^{2+}$ for arsenic sulphide sol increases in the order:

• A. $A{l}^{3+}<B{a}^{2+}<N{a}^{+}$
• B. $N{a}^{+}<B{a}^{2+}<A{l}^{3+}$
• C. $B{a}^{2+}<N{a}^{+}<A{l}^{3+}$
• D. $A{l}^{3+}<N{a}^{+}<B{a}^{2+}$

Answer 1

The correct option is B $N{a}^{+}<B{a}^{2+}<A{l}^{3+}$

Arsenic sulphide sol is a negatively charged sol. According to Hardy Schulz rule, greater the charge on cation greater is its coagulating power for negatively charged particle. Hence the correct order is $N{a}^{+}<B{a}^{2+}<A{l}^{3+}$