Question

A pair of solute and solvent that cannot form colloidal solution

Answer 1

Answer:

A colloid is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium.

The essential difference between a solution and a colloid is that of particle size. While in a solution, the constituent particles are ions or small molecules. In a colloid, the dispersed phase may consist of particles of a single macromolecule (such as protein or a synthetic polymer) or an aggregate of many atoms, ions or molecules. 

Gas-gas colloidal system is not possible as we can't distinguish between the dispersed phase and dispersed medium.