What is meant by negative deviation from Raoult's law and how is the sign of `Delta_("mix")H` related to negative deviation from Raoult's law ?

Explanation

`to` When the vapour pressure of a solution is lower than the predicted value by Raoult's law, it is called negative deviation.
`to` In case of negative deviation the inter molecular attractive forces between 1 - 1 and 2 - 2 are weaker than those between 1 - 2.
`to` It leads to decrease in vapour pressure resulting in negative deviation.
`to` The vapour pressure diagram showing negative deviation as follows.
`to` Eg. : `"HNO"_(3)` and water, HCl and water.