Colloidal solutions of metals like gold can be prepared when their salt solutions react with certain substances like SnClâ‚‚, formaldehyde, phenyl hydrazine, etc.
2AuCl₃ ​ + 3SnCl₂ ​ → 3SnCl₄​ + 2Ausol ​
The above method is an example of
a)Reduction method
b)Oxidation method
c)Hydrolysis method
d)Double decomposition method
