Solubility of bitumen: in which of the following liquids does bitumen dissolve for testing and extraction purposes? (Select the standard laboratory solvent used for bituminous binders.)

Introduction / Context:
Bitumen is a complex mixture of hydrocarbons that is insoluble in water but soluble in certain organic solvents. Solubility testing helps assess purity and binder content in bituminous mixes. The question asks for the classic solvent used in laboratory extraction and solubility tests.

Given Data / Assumptions:

• Bitumen is hydrophobic.
• Standard organic solvents can dissolve bitumen for analysis.
• Carbon disulphide (CS2) has long been used as a reference solvent in test methods.

Concept / Approach:
Water, carbon dioxide, and brine do not dissolve bitumen. Laboratory protocols historically use carbon disulphide (and, in modern practice, safer alternatives like trichloroethylene or toluene) to dissolve and recover bitumen from mixes. The canonical answer remains carbon disulphide for classic tests.

Step-by-Step Solution:

Verification / Alternative check:
Traditional test methods reference CS2 as the solvent of choice for solubility and extraction; some modern labs substitute other organics for safety, but principle stands.

Why Other Options Are Wrong:

• Carbon dioxide: not a solvent for bitumen in standard conditions.
• Water / Sodium chloride solution: bitumen is water-insoluble.
• None of these: incorrect because CS2 is valid.

Common Pitfalls:
Assuming any organic liquid works equally well; safety protocols are essential when handling volatile solvents like CS2.

Final Answer:
Carbon disulphide