Question

Match the dyes given in List-I with their description given in List-II:

List-I (Dyes)	List-II (Description)
(A) Reactive	(I) Applied to fabric as a reduced, water soluble leuco compound
(B) Sulphur	(II) Developed for dyeing acetate fibers
(C) Disperse	(III) Water insoluble dyes
(D) Vat	(IV) Reacts with the fiber molecule by addition or substitution

Choose the correct answer from the options given below:

• (A) - (IV), (B) - (III), (C) - (II), (D) - (I)
• (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
• (A) - (I), (B) - (II), (C) - (IV), (D) - (III)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

Vat dyes always involve the "leuco" reduction and oxidation steps.
Reactive dyes are the only class that chemically reacts to form covalent bonds with the fiber molecules.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Dyes are organic chemical compounds that selectively bind to specific textile fibers via ionic, hydrogen, covalent, or physical bonds.

Step 2: Detailed Explanation:
Let us match each dye class to its specific chemical description:
1. Reactive dyes (A): These dyes form a stable covalent bond (via substitution or addition reactions) with the hydroxyl groups of cellulosic fibers, offering excellent wash fastness. Thus, (A) matches (IV) Reacts with the fiber molecule by addition or substitution.
2. Sulphur dyes (B): These are highly economical, water-insoluble complex organic dyes containing sulfur linkages. Thus, (B) matches (III) Water insoluble dyes.
3. Disperse dyes (C): These are non-ionic, hydrophobic dyes developed specifically to dye hydrophobic acetate and synthetic (polyester) fibers. Thus, (C) matches (II) Developed for dyeing acetate fibers.
4. Vat dyes (D): These are water-insoluble dyes (such as Indigo) that must be chemically reduced to a water-soluble "leuco" compound using a reducing agent before application, followed by oxidation to restore insolubility inside the fiber. Thus, (D) matches (I) Applied to fabric as a reduced, water-soluble leuco compound.
This gives the combination: (A) - (IV), (B) - (III), (C) - (II), (D) - (I).

Step 3: Final Answer
The correct option is (A).