Which of the following statements is/are true?
I. The hydrocarbon methane (CH₄) will dissolve completely in acetone (CH₃COCH₃).
II. Ammonia (NH₃) will form a heterogeneous mixture with carbon tetrachloride (CCl₄).
III. Pentane (C₅H₁₂) will form a homogeneous mixture with carbon tetrabromide (CBr₄).
IV. Methanethiol (CH₃SH) is miscible in fluoromethane (CH₃F).

• A. I only
• B. II and III
• C. II, III, IV
• D. III and IV
• E. None of the above

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of solubility and miscibility. Solubility refers to the ability of a substance to dissolve in a solvent, forming a homogeneous mixture. Miscibility is a specific type of solubility where two liquids can mix in all proportions, forming a single phase.
2. Step 2: Analyze statement (a): Methane is a nonpolar molecule, while acetone is a polar solvent. Generally, 'like dissolves like,' meaning polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes. Therefore, methane is unlikely to dissolve completely in acetone.
3. Step 3: Analyze statement (b): Hydrofluoric acid (HF) is polar, while carbon tetrachloride (CCl4) is nonpolar. Due to their differing polarities, HF and CCl4 will not mix well, likely forming a heterogeneous mixture.
4. Step 4: Analyze statement (c): Pentane and carbon tetrabromide (CBr4) are both nonpolar substances. Nonpolar substances tend to mix well with each other, forming a homogeneous mixture.
5. Step 5: Analyze statement (d): Methanethiol (CH3SH) and fluoromethane (CH3F) are both polar molecules. Polar molecules are generally miscible with each other, so methanethiol is likely miscible in fluoromethane.