# Which of the following statements about Raoult's Law is/are correct?

(1) Less volatile mixture $\rightarrow$ positive deviation

(2) More volatile mixture $\rightarrow$ negative deviation

(3) Less volatile mixture $\rightarrow$ negative deviation

(4) More volatile mixture $\rightarrow$ positive deviation

Answer: Statements (3) and (4) are both correct.
When the mixture is less volatile,the total pressure is less than the pressure calculated as per Raoult's law. Hence there is a negative deviation. Similarly, when the mixture is more volatile, there is a positive deviation..
edited Jul 15, 2014