potense of hydrogen or power of hydrogen is basically a test used to determine strengh of a acid or a base.
pH means power of hydrogen/ povouir hydrogen, means concentration of hydrogen ions in an aqueous solution.So it is used to identify whether a substance is acid,base or neutral.
Alkalies are the bases that are soluble in water.Some bases are not soluble in water they are not called alkalies
so i hope you know what a mixture is. well a mixture a mixture is two or more elements or compounds mixed together but not chemically combined are called mixtures . they can be easily seperated. example: air is mixture of gases like nitrogen oxygen etc. now a heterogenious mixture is a mixture that composes of components that are not uniform and have totally different properties. i hope this answer helps.