Why the colour of gold sol change with the size of gold particles?

Which out of gold sol and gelatin in water sol is a lyophilic sol?

Assertion : Gold and silver are extracted from their native ores by leaching. Reason : Both silver and gold particles dissolve in dilute solution of sodium cyanide in presence of oxygen.

Assertion : Aqueous gold colloidal sol is red in colour. Reason : The colour arised due to scattering of light by particles of gold.

Fool's gold is

Assertion: A quious gold colloidal solution is red in colour. Reason: The colour arises due to scattering of light by colloidal gold particles.

Given below are a few electrolytes, indicate which one among them will bring about the coagulation of a gold sol quickest and in the least of concentration ?

Alchemists changed iron into gold.

Haemoglobin and gold sol are examples of

Haemoglobin and gold sol are examples of

A gold sol is prepared by :