Question

Gold sol is not a
(A)- Lyophobic sol
(B)- Negatively charged sol
(C)- Macromolecular sol
(D)- Multimolecular colloid

Answer 1

Hint: Gold sol contains a large number of particles of various sizes having several atoms of gold. Lyophobic sols like sols of metals are unstable and generally have negative charge on them.

Complete step by step answer:
Let us look at the characteristics of a gold sol and try to find the answer to the question.
Lyophobic sols are the sols formed by substances like metals, and their sulphides which when mixed do not form the colloidal sol directly. These sols are formed by special methods and are generally unstable. Gold sol being a sol of gold (Au) metal is thus, a lyophobic sol.
Metal sols are generally negatively charged. Therefore, gold sol is also a negative charged sol.
Macromolecular colloids are formed when macromolecules having large molecular masses are dissolved in a dispersion medium. But in gold sol there are no large molecular mass molecules but a large number of small molecules which are joined together to form colloidal particles. Hence, gold sol is not a macromolecular colloid.
Multimolecular colloids are formed on dissolution of a large number of small atoms or molecules aggregate together to form colloidal sol. Gold sol contains a large number of particles of various masses and sizes consisting of several gold atoms. Hence, gold sol is a multimolecular colloid.
Therefore, we conclude that gold sol is a multimolecular, lyophobic and negatively charged sol. it is not a macromolecular colloid.
So, the correct answer is “Option C”.

Note: We are likely to get confused between macromolecular and multimolecular colloids. Carefully note the characteristics and conditions for lyophobic, multimolecular and macromolecular colloids. Multi means many so, in multimolecular many different particles combine to give a colloidal size particle whereas in macromolecular colloids, individual particles have colloidal size.