Question

1.14
(c) 3.6 (d) 5
4. Which of the following on addition in 1.0 molal KI solution will give rise to increase in vapour pressure ?
(a) Hgl2
(b) 12
(c) NaCl
(d) Na2SO4
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Answer 1

When KI reacts with I₂ , it gives KI₃ which decreases the van't hoff factor of the solute and thus Relative lowering of vapour pressure is directly proportional to Van't Hoff Factor , so Relative lowering of V.P. is less , which means more vapour pressure.

(b) I₂