Step 1: Understand milk of magnesia.
Milk of magnesia is a colloidal suspension of
\[
Mg(OH)_2
\]
in water.
It behaves as an antacid and is commonly used to neutralize excess hydrochloric acid present in the stomach.
Step 2: Write the neutralization reaction.
The excess stomach acid reacts with magnesium hydroxide as:
\[
Mg(OH)_2+2HCl \rightarrow MgCl_2+2H_2O
\]
This reduces acidity and relieves stomach disorders such as acidity and indigestion.
Step 3: Analyze other options.
Silver sol: Mainly used for its antiseptic properties.
Antimony sol: Not used for stomach disorders.
Gold sol: Mainly used in medicinal and research applications, not as an antacid.
Hence, milk of magnesia is the correct choice.
Step 4: Final conclusion.
Therefore, the colloidal solution used to treat stomach disorders is
\[
\boxed{\text{Milk of magnesia}}
\]