Question

Match List - I with List - II.

List - I	List - II
A. Urea	I. Reducing Agent
B. Sodium Hydrosulphite	II. Hygroscopic Agent
C. Sodium Dichromate	III. Wetting Agent
D. Turkey Red Oil	IV. Oxidizing Agent

Choose the correct answer from the options given below :

• A. \( \text{A-I, B-II, C-III, D-IV} \)
• B. \( \text{A-I, B-III, C-II, D-IV} \)
• C. \( \text{A-II, B-I, C-IV, D-III} \)
• D. \( \text{A-II, B-IV, C-I, D-III} \)

Hint:

Sodium Hydrosulphite is the most common reducing agent in textile chemistry. If you match B-I, you can often narrow down the options significantly.

Answer 1

The Correct Option is C

Concept: Auxiliary chemicals are used in textile dyeing and printing to facilitate the process, improve dye penetration, or ensure proper chemical reactions.

Step 1: Evaluate the role of each chemical auxiliary.

• Urea: In printing pastes, it acts as a Hygroscopic Agent. It absorbs moisture from the air during the steaming process, which helps in dissolving the dye and assisting its penetration into the fiber.
• Sodium Hydrosulphite: Commonly known as "hydro," it is a powerful Reducing Agent. It is essential in vat dyeing (like Indigo) to convert the water-insoluble dye into its soluble "leuco" form.
• Sodium Dichromate: This is used as an Oxidizing Agent. It is often used in the after-treatment of certain dyes to develop the final color or to convert leuco dyes back into their insoluble state within the fiber.
• Turkey Red Oil (TRO): This is a sulfonated castor oil that acts as a Wetting Agent and surfactant. it reduces the surface tension of the water, allowing the dye liquor to wet out the fabric more evenly and quickly.