States of Matter - Result Question 1-1
1. The qualitative sketches I, II and III given below show the variation of surface tension with molar concentration of three different aqueous solutions of $\mathrm{KCl}, \mathrm{CH}_3 \mathrm{OH}$ and $\mathrm{CH}_3\left(\mathrm{CH}2\right){11} \mathrm{OSO}_3^{-} \mathrm{Na}^{+}$at room temperature.
The correct assignment of the sketches is
(d) $\mathrm{CH}_3 \mathrm{OH}$ $ \quad \quad \quad \quad \quad KCl \quad \quad \quad \quad $ $\mathrm{CH}_3\left(\mathrm{CH}2\right){11} \mathrm{OSO}_3^{-} \mathrm{Na}^{+}$
(2016 Adv.)
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Answer:
Correct Answer: 1. (d)
Solution:
I $\left(\mathrm{CH}_3 \mathrm{OH}\right)$ : Surface tension decreases as concentration increases.
II (KCl) : Surface tension increases with concentration for ionic salt.
III $\left[\mathrm{CH}_3\left(\mathrm{CH}2\right){11} \mathrm{OSO}_3^{-} \mathrm{Na}^{+}\right]$: It is an anionic detergent.
There is decrease in surface tension before micelle formation, and after CMC (Critical Micelle Concentration) is attained, no change in surface tension.
BETA
