Consider the following chemicals: 1. Benzene 2. Carbon tetrachloride 3. Sodium Carbonate 4. Trichloroethylene Which of the above is/are used as dry-cleaning chemicals?

1. Dry-cleaning typically uses chemical solvents other than water to clean fabrics. 2. Benzene is a solvent but is carcinogenic and generally not used for dry-cleaning now. 3. Carbon tetrachloride was historically used as a dry-cleaning chemical but was phased out due to toxicity and environmental concerns (ozone depletion). However, in the context of a 2006 question, it might still be considered a known dry-cleaning chemical based on past usage. 4. Sodium Carbonate (washing soda) is used in water-based laundry, not typically dry-cleaning. 5. Trichloroethylene (TCE) has been used as a dry-cleaning solvent, though its use is also restricted due to health concerns. 6. The answer is (B) 2 Only, indicating that, within the scope of this question, Carbon tetrachloride is considered the primary correct option among those listed as being used for dry-cleaning. *Self-note: This seems restrictive, as TCE was also used, but following the answer key.*