Question

Raoult’s law is obeyed by each constituent of a binary liquid solution when:
A. The forces of attraction between like molecules are greater than those between unlike molecules.
B. The forces of attraction between like molecules are smaller than those between unlike molecules.
C. The forces of attraction between like molecules are identical than those between unlike molecules.
D. The volume occupied by molecules is different.

Answer 1

Hint: You should know that Raoult's law is a kind of law which is only for and followed by ideal solutions of two components. Now, it will be easy to figure out in ideal solutions, what will be the forces of attraction between the like and unlike molecules.

Complete answer:
Let us first have knowledge about Raoult's law.
Raoult’s law was named for the law of the French pharmacist Francois Marie Raoult, who discovered while his study that, the vapour pressure of a solution decreased simultaneously when substances were mixed in the solution.
The law states that, in a solution (or mixture) the partial vapour pressure of a solvent is equal to or identical with a pure solvent vapour pressure multiplied in a solution by the molar fraction.
Raoult’s law is the law only applicable for ideal solutions of two same or different components. Now as per given, in the case of an ideal binary solution (i.e. having two components), the total force of attraction between the like molecules should be exactly same as that of between unlike molecules. So that, even before mixing whatever was the force at beginning should have to be the same as the total force of attraction even after mixing of the components. Then only the mixture will be called as an ideal solution and therefore the total pressure of each component can be added to give the total pressure of the solution, thus following Raoult's law.
So, the forces of attraction between like molecules are identical than those between unlike molecules, thus following Raoult's law.

Hence, the correct option is C.

Note:
It is important to note that Raoult's law is only suitable for ideal solutions. But ideal solutions are difficult to find and are rare in the surrounding. As many of the liquids in the mixture do not consist of the same attractive forces, such solutions try to deviate from the law.