Which of the following are mixtures?  I. Petroleum  II. Rubber latex  III. Vulcanizer's solution  IV. Carbon sulphide

To solve this question, we need to distinguish between pure substances (elements and compounds) and mixtures (physical combinations of substances that can be separated by physical means).

1. Analyze the components

• I. Petroleum (Crude Oil): This is a complex mixture of various hydrocarbons (alkanes, cycloalkanes, and aromatic hydrocarbons) along with small amounts of sulfur, nitrogen, and oxygen compounds. It is separated into useful fractions (like petrol, kerosene, and diesel) through fractional distillation. It is a mixture.
• II. Rubber Latex: This is a colloidal suspension of rubber particles in water, along with proteins, alkaloids, and resins. Because it contains various substances suspended in a liquid medium, it is a mixture.
• III. Vulcanizer's Solution: This is a solution of rubber in a solvent like benzene or carbon disulfide. Since it involves a solute dissolved in a solvent, it is a mixture.
• IV. Carbon Disulphide ($CS_2$): This is a chemical compound consisting of one carbon atom and two sulfur atoms bonded together in a fixed ratio. Because it has a constant chemical composition and properties, it is a pure compound, not a mixture.

2. Evaluate the options

• I, II, and III are all mixtures.
• IV is a pure compound.

Therefore, the group that consists of mixtures is I, II, and III.

3. Conclusion

Comparing our analysis to the provided options, we find that Option A correctly identifies the mixtures.

Exam Tip

When you see questions about mixtures in Chemistry, remember:

• Mixtures are usually "solutions," "suspensions," "colloids," or "crude" substances.
• Compounds usually have a specific chemical formula (like $H_2O$, $NaCl$, or $CS_2$) and are formed by chemical bonding, not just physical mixing.