Correct Option
Dry cleaning is a process that employs non-aqueous chemical solvents for cleaning fabrics. The chemicals listed have been used or are associated with dry cleaning processes in various capacities:
- Benzene (1): Historically, benzene was utilized as a solvent in dry cleaning due to its effectiveness in dissolving organic compounds. However, its use has been largely discontinued owing to its carcinogenic nature.
- Carbon tetrachloride (2): This compound was also a commonly used dry cleaning agent. Its application has been significantly restricted due to its toxicity, particularly its hepatotoxic effects, and its classification as an ozone-depleting substance.
- Trichloroethylene (4): Trichloroethylene is an effective solvent widely employed in dry cleaning, especially for industrial degreasing and garment cleaning, although its use is subject to environmental and health regulations.
- Sodium carbonate (3): Sodium carbonate, also known as washing soda, is a water-soluble salt. It is primarily used in aqueous solutions for laundry detergents, bleaching, and water softening, and is not a solvent used in non-aqueous dry cleaning processes.
Therefore, Benzene, Carbon tetrachloride, and Trichloroethylene are or have been used as dry cleaning chemicals.
Incorrect Options
Options (a) and (b) are incorrect because they are incomplete, excluding other relevant chemicals (Carbon tetrachloride and Trichloroethylene for (a); Benzene and Trichloroethylene for (b)) that have been or are used in dry cleaning. Option (d) is incorrect as it erroneously includes Sodium carbonate, which is not a dry cleaning solvent but an additive for aqueous cleaning processes.