Multiple choice

Which of the following dyes are used as pH indicators and as biological stains?

  1. Acid dyes

  2. Basic dyes

  3. Direct dyes

  4. Vat dyes

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

 Direct dyes are used on cotton, paper, leather, wool, silk and nylon. They are also used as pH indicators and as biological stains.