Question

Castor oil is a

• A. Volatile oil
• B. Wax
• C. Oleo-resin
• D. Fixed oil

Hint:

Fixed oils, like castor oil, do not evaporate and are typically derived from seeds.

Answer 1

The Correct Option is D

Step 1: Understanding castor oil.
Castor oil is a non-volatile oil that is derived from the seeds of the castor bean plant (*Ricinus communis*). It is considered a fixed oil, meaning it does not evaporate like volatile oils.
Step 2: Analyzing the options.
(A) Volatile oil: Volatile oils, such as essential oils, evaporate easily and are not fixed oils. Castor oil is not a volatile oil.
(B) Wax: This is incorrect, as castor oil is not a wax.
(C) Oleo-resin: Oleo-resins are a mixture of oil and resin, which does not apply to castor oil.
(D) Fixed oil: Correct — Castor oil is a fixed oil, meaning it is not volatile and remains stable at room temperature.
Step 3: Conclusion.
The correct answer is (D) Fixed oil as castor oil is a fixed, non-volatile oil.

Answer 2

We can settle this by sorting oils/fats into their standard pharmacognosy categories and seeing which one castor oil actually belongs to.

1. Volatile oil: Volatile (essential) oils are aromatic, evaporate readily at room temperature, and leave no permanent greasy stain on paper. Castor oil is odourless in this sense and does not evaporate away, so it fails this test.
2. Wax: Waxes are esters of long-chain fatty acids with long-chain monohydric alcohols (not glycerol), and are typically solid or semi-solid at room temperature. Castor oil is a liquid glyceride, not an ester of this wax type.
3. Oleo-resin: Oleo-resins are natural mixtures of an essential oil dissolved in a resin (as in turpentine or copaiba), a combination not present in castor oil's composition.
4. Fixed oil: Fixed oils are glyceryl esters of fatty acids (triglycerides) that remain oily and non-volatile at ordinary temperatures and leave a permanent translucent grease stain on paper. Castor oil, extracted from Ricinus communis seeds and composed mainly of the triglyceride of ricinoleic acid, fits this description exactly.

Testing castor oil against the standard "does it evaporate, is it a glyceride, does it leave a permanent grease stain" criteria places it squarely in the fixed oil category.

Therefore, the correct answer is Fixed oil.