Propene, being an alkene, and propyne, being a alkyne, are distinguished using the common chemical tests namely ammoniacal silver nitrate or ammoniacal cuprous chloride. Ammoniacal silver nitrate is also called as Tollen's reagent.
Starch aqueous solution is a lyophilic colloidal solution.
Lyophilic colloids are liquid loving colloids. When these colloids are mixed with suitable liquid high force of attraction exists between colloidal particles and liquid.