How many phases are present in a colloidal solution?

Which sol is used as an intramuscular injection?

Which characteristic is true in respect of colloidal particles?

Which one is an example of a multimolecular colloid system?

$A$ $42.12 \% (w/v)$ solution of $NaCl$ causes precipitation of a certain sol in $10 \, hours$. The coagulating value of $NaCl$ for the sol is $.....$
[Given : Molar mass : $Na = 23.0 \, g \, mol^{-1} ; Cl = 35.5 \, g \, mol^{-1}]$

In which of the following sols are the colloidal particles negatively charged?