Discussion Forum



1)

The qualitative sketches I, II and III given below show the variation of surface tension with the molar concentration of three different aqueous solutions of KCI.CH3 OH and  $CH_{3}(CH_{2})_{11}OSO_{3}^{-}Na^{+}$ at  room temperature

1222021206_c3.JPG

The correct assignment of the sketches is 


A) $I. KCI, II. CH_{3}OH, III. CH_{3}(CH_{2})_{11}OSO_{3}^{-}Na^{+}$

B) $ I. CH_{3}(CH_{2})_{11}OSO_{3}^{-}Na^{+}, II. CH_{3}OH, III. KCI.$

C) $ I. KCI, II. CH_{3}(CH_{2})_{11}OSO_{3}^{-}Na^{+}, III. CH_{3}OH.$

D) $ I. CH_{3}OH, II. KCI, III. CH_{3}(CH_{2})_{11}OSO_{3}^{-}Na^{+}.$

Answer:

Option D

Explanation:

$ I. (CH_{3}OH)$: Surface tension

decreases as concentration increases.

II. (KCI): Surface tension increases with concentration for ionic salt.

III. $[CH_{3}(CH_{2})_{11}OSO_{3}^{-}Na^{+}].$: It is an anionic detergent.

  There is a decrease in surface tension before micelle formation. and after CMC (Critical Micelle Concentration) is attained. no change in surface tension.

1222021286_c4.JPG