Multiple choice Which of the following dyes cannot be used for cotton? Acid dyes Basic dye Ingrain dyes Vat dyes Reveal answer Fill a bubble to check yourself A Correct answer Explanation Acid dyes are sodium salts of sulphonic acid and nitrophenols. They are used for dyeing animal fibres such as wool and silk, but not vegetable fibres like cotton. The dye solution is acidified with sulphuric or acetic acid.