Multiple choice

Which one of the following is an example of a basic dye?

  1. Martius yellow

  2. Malachite green

  3. Alizarin

  4. Phenolphthalein
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Basic dyes are cationic dyes that contain amino or substituted amino groups which become positively charged in solution. Malachite green (Basic Green 4) is a triphenylmethane dye with dimethylamino groups that carry a positive charge, allowing it to bind to negatively charged surfaces like acrylic fibers and biological tissues for staining. Martius yellow is an acid dye, Alizarin is a mordant dye, and Phenolphthalein is a pH indicator.

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