Solutions Question 72
Question: The freezing point of one molal $ NaCl $ solution assuming $ NaCl $ to be 100% dissociated in water is (molal depression constant = 1.86) [CPMT 1985; BHU 1981; MP PMT 1997; UPSEAT 2001]
Options:
A) $ -{{1.86}^{o}}C $
B) $ -{{3.72}^{o}}C $
C) $ +{{1.86}^{o}}C $
D) $ +{{3.72}^{o}}C $
Show Answer
Answer:
Correct Answer: B
Solution:
For $ NaCl $
$ i=2 $
$ \Delta T_{f}=2K_{f}m=2\times 1.86\times 1=3.72 $
$ T_{s}=T-\Delta T_{f}=0-3.72=-3.72{}^\circ C $
