Multiple choice

Iodine turns bluish black on reacting with _____.

  1. alcohol

  2. starch

  3. glucose

  4. none of these

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Iodine solution reacts specifically with starch to produce a characteristic blue-black color, which is a standard test for starch presence. It does not react this way with alcohol or glucose.