# starch can be used as an indicator for the detection of traces of

$\begin{array}{1 1}(a)\;\text{Protein in blood}\\(b)\;\text{Urea in blood}\\(c)\;I_2\text{ in aq. solution}\\(d)\;\text{Glucose in aq. solution}\end{array}$

$I_2$ in aq. solution
The iodine test is used to test for the presence of starch. Starch turns an intense "blue-black" colour upon addition of aqueous solutions of the triiodide anion, due to the formation of an intermolecular charge-transfer complex. In the absence of starch, the brown colour of the aqueous solution remains.
Hence (c) is the correct answer.
answered Mar 26, 2014
edited Jan 29