Explanation:

When a paper strip is immersed in NaOH (sodium hydroxide) and then in carbon disulphide (CS2), the liquid obtained is viscose.

Viscose:
Viscose is a type of rayon fabric that is made from regenerated cellulose fibers. It is produced by treating cellulose, usually from wood pulp, with NaOH and carbon disulphide. This process is known as the viscose process.

Process:
1. Sodium hydroxide (NaOH) is a strong base that is used to break down the cellulose fibers in the paper strip. It hydrolyzes the cellulose into individual glucose molecules.
2. The paper strip is then immersed in carbon disulphide (CS2) which dissolves the cellulose glucose molecules.
3. The resulting liquid is a solution of cellulose in CS2, which is called viscose.

Key Points:
- NaOH is used to break down the cellulose fibers in the paper strip.
- Carbon disulphide dissolves the cellulose glucose molecules.
- The resulting liquid is called viscose.

Therefore, the correct answer is option 'B' - Viscose.

To determine the liquid obtained when a paper strip is immersed in NaOH and then in carbon disulphide (Cs₂), we need to understand the reactions that occur with different types of materials.
When immersed in NaOH, the paper strip undergoes a reaction known as saponification. This reaction breaks down the ester bonds present in fatty acids of the paper, resulting in the formation of soap. The soap dissolves in water, forming a soapy solution.
Next, when the paper strip is immersed in carbon disulphide (Cs₂), it is used to extract any remaining organic compounds present. Carbon disulphide is a nonpolar solvent that can dissolve nonpolar substances.
Based on these reactions, we can determine the liquid obtained:
- Nylon: Nylon is a synthetic polymer that is not affected by NaOH or carbon disulphide. Therefore, the liquid obtained is not nylon.
- Viscose: Viscose, also known as rayon, is a semi-synthetic fiber made from cellulose. When immersed in NaOH, viscose dissolves and forms a viscous solution. When further immersed in carbon disulphide, viscose does not dissolve. Therefore, the liquid obtained is viscose.
- Plastic: Plastic is a broad term that encompasses a wide range of materials. However, most plastics are not soluble in NaOH or carbon disulphide. Therefore, the liquid obtained is not plastic.
- Cellulose: Cellulose is the main component of paper. When immersed in NaOH, cellulose undergoes saponification and forms a soapy solution. When further immersed in carbon disulphide, the remaining organic compounds are dissolved. Therefore, the liquid obtained is cellulose.
Therefore, the correct answer is B: Viscose.