Which of the following oils is most likely to spontaneously ignite on rags left in the open due to rapid oxidation?

• A. Vegetable shortening
• B. Mineral oil
• C. Linseed oil
• D. Olive oil

Answer: (C)

Verified step by step guidance

1. Understand that spontaneous ignition of oils on rags is related to the oil's tendency to undergo rapid oxidation, which generates heat. If the heat is not dissipated, it can build up and cause the material to ignite.
2. Recognize that oils with a higher degree of unsaturation (more double bonds in their fatty acid chains) oxidize more rapidly because double bonds are more reactive sites for oxygen.
3. Identify the types of oils given: vegetable shortening (mostly saturated or partially hydrogenated fats), mineral oil (a petroleum product, not prone to oxidation), linseed oil (highly unsaturated, rich in polyunsaturated fatty acids), and olive oil (mostly monounsaturated).
4. Conclude that linseed oil, being highly unsaturated, is most prone to rapid oxidation and heat generation, making it the most likely to spontaneously ignite on rags left in the open.
5. Summarize that the key factor is the degree of unsaturation in the oil, which correlates with its oxidation rate and risk of spontaneous combustion.