Surface Chemistry - Result Question 20
21. The coagulating power of electrolytes having ions $Na^{+}, Al^{3+}$ and $Ba^{2+}$ for arsenic sulphide sol increases in the order
(a) $\mathrm{Al}^{3+}<\mathrm{Ba}^{2+}<\mathrm{Na}^{+}$
(b) $\mathrm{Na}^{+}<\mathrm{Ba}^{2+}<\mathrm{Al}^{3+}$
(c) $\mathrm{Ba}^{2+}<\mathrm{Na}^{2+}<\mathrm{Al}^{3+}$
(d) $\mathrm{Al}^{3+}<\mathrm{Na}^{+}<\mathrm{Ba}^{2+}$
(2013 Main)
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Answer:
Correct Answer: 21. (d)
Solution:
According to Hardy Schulze rule, greater the charge on oppositely charged ion, greater is its coagulating power. Since arsenic sulphide is a negatively charged sol, thus, the order of coagulating power is $\mathrm{Na}^{+}<\mathrm{Ba}^{2+}<\mathrm{Al}^{3+}$ .
BETA
