The Chemical Name of ” hypo” Commonly Used in Photography is

Answer: (1) Sodium thiosulphate

Sodium thiosulfate is the chemical name of “Hypo”. The chemical formula of “Hypo” is _{Na2S2O3 It is easily soluble in in water and it is not soluble in silver salt. It is a colorless crystal of sodium, sulfur, hydrogen and Oxygen.} 

It is used in chemical manufacture and chrome – tanning  leather. It is mostly used in photography for developing film.