Question

Which of the following is(are) the properties of sols?
(This question has multiple correct options)
A. Adsorption
B. Tyndall effect
C. Flocculation
D. Paramagnetism

Answer 1

Hint: A sol is a type of a colloid which is made up of very tiny solid particles suspended in a liquid medium. In simple words, the dispersing medium of a sol is liquid whereas the dispersing phase of a sol is solid. The solid particles are stable enough and hence do not settle down in liquid when left undisturbed.

Complete answer: Different properties of sols are as follows:
Adsorption: It is a process in which the molecule of a gas or a liquid sticks to the surface of the solid forming a thin film. In sols, solids are not dissolved in the liquid medium. Thus, the molecules of liquid act as adsorbate and attach to the surface of solid which acts as an adsorbent to show adsorption. This linkage of liquid molecules with the surface of solids is one of the major reasons that solid particles do not settle down when left undisturbed.
Tyndall effect: The phenomenon of scattering of light in a very fine suspension or a colloid is known as the Tyndall effect. It is also termed as Tyndall scattering. In this process, the solid particles present in the sols block the way of the light due to which the path of light changes and scattering is observed.
Flocculation: when a sol is colloidally unstable that means the rate of adsorption is too low i.e., the cohesion of liquid particles with solid is less, then the solid particles settle down in the liquid in the form of floc and the phenomenon is known as flocculation.
Hence, options (A), (B) and (C) are the correct answers.

Additional information-
Paramagnetism is a type of magnetism in which some materials are weakly attracted if an external magnetic field is applied and form induced, internal magnetic fields in the direction of magnetic field which is applied externally. It is solely a solid property. Hence, it is not a characteristic property of sols.

Note:
It is important to note that due to the formation of associated molecules in a colloidal sol, the observed values of colligative properties like osmotic pressure, elevation in boiling point, depression in freezing point and relative decrease in vapor pressure are smaller than expected values as compared to a true solution.