Which of the following additives improves the cetane number of diesel?

Solution(By Examveda Team)

Option A: Amyl nitrate - Amyl nitrate is not commonly used as an additive to improve the cetane number of diesel. It is more commonly associated with other applications, such as as a vasodilator or in the production of explosives.

Option B: Ethyl mercaptan - Ethyl mercaptan is a compound used primarily as an odorant in natural gas and propane. It is not used to improve the cetane number of diesel fuel.

Option C: Napthenic acid - Napthenic acid is a type of organic acid found in petroleum. While it is sometimes used as an additive in lubricating oils, it is not used to improve the cetane number of diesel.

Option D: Tetra ethyl lead - Tetra ethyl lead is the correct additive that improves the cetane number of diesel fuel. It enhances the ignition quality of diesel, leading to smoother engine operation and lower emissions.

Conclusion:
Among the options provided, Option D: Tetra ethyl lead is the correct additive used to improve the cetane number of diesel fuel. Therefore, the correct answer is Option D.