A) 0.70
B) 0.50
C) 0.90
D) 0.80
Correct Answer: A
Solution :
Relative lowering of vapour pressure = mole fraction of solute (Raoults law) \[\frac{p-{{p}_{s}}}{p}={{\chi }_{2}}\] \[\frac{p-{{p}_{s}}}{p}=\frac{wM}{mW}\] \[0.0125=\frac{wM}{mW}\] or \[\frac{w}{mW}=\frac{0.0125}{18}=0.00070\] Hence, \[molality=\frac{w}{mW}\times 1000\] \[=0.0007\times 1000=0.70\]You need to login to perform this action.
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