Based on your pre-lab calculation (see lab manual), what is the threshold concentration of iodine required for the solution to turn blue?Question 9Answer2.50 × 10–3 mol/L2.00 × 10–5 mol/L5.00 × 10–3 mol/L4.00 × 10–5 mol/L1.25 × 10–3 mol/L

20.State a control variable if you're investigating the effect of pH on the time taken for iodine to remain yellow.

odine tests for the presence of starch. Iodine is yellow, but turns blue/black when exposed to starch. You will add iodine to a tube of water (the test solution). If there is NOT starch in the test solution, what color should the solution be?Group of answer choicesBlue/blackYellowPink

4. A reaction mixture initially containing vitamin C at 0.0112 M, H2O2 at 0.14 M, and iodide ion at 0.03 M. The mixture turns from colorless to dark blue-black after 24.7 seconds. Calculate the rate of this reaction if the final iodide concentration is 0.013 M.

16.State the independent variable if you're investigating the effect of pH on the time taken for iodine to remain yellow.

iodine is titrated with thiosulfate. What color change signals the endpoint?A.Green to blueB.Blue to greenC.Blue to clearD.Clear to blue