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) $Al^{3+}<Ba^{2+}<Na^{+}$
(b) $Na^{+}<Ba^{2+}<Al^{3+}$
(c) $Ba^{2+}<Na^{2+}<Al^{3+}$
(d) $Al^{3+}<Na^{+}<Ba^{2+}$
(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 $Na^{+}<Ba^{2+}<Al^{3+}$.
