Since indigo is highly insoluble, it must first be reduced to form a water‐soluble derivative, leucoindigo, to be used as a fabric dye. Which reagent did you use to reduce indigo?
a. 10% NaOH solution
b. 10% Na2S2O4 solution
c. 10% NaHCO3 solution
d. 10% NaCl solution
e. 5% NaOH solution
Answer: b. 10% Na2S2O4 solution