Flash point of a fuel is the temperature at which
Answer: A
It is a safety property governing storage and handling rather than a performance one. Autoignition temperature is the quite separate property described by the last option. Storage classification depends on the flash point.
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Pour point of an oil is the temperature at which it
Answer: B
Wax crystallising out of the oil is usually what stops the flow, so dewaxing or a pour point depressant is used for cold climates. It is a handling property rather than a chemical one. Wax crystals are what arrest the flow.
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Match each product property with the product it principally characterises.
List I
A. Octane number
B. Cetane number
C. Smoke point
D. Viscosity index
List II
1. kerosene and jet fuel
2. motor gasoline
3. lubricating oil
4. diesel fuel
Answer: C
Each specification exists because a particular engine or application is sensitive to that property. Quoting the wrong number for a product is a common slip in reading a refinery flowsheet. Each is measured by its own standard test.
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Viscosity index of a lubricating oil measures
Answer: D
Correct answer: how little viscosity changes with heat
The viscosity index is a dimensionless number describing the *slope* of viscosity against temperature: a high index means the oil thins less as it warms, so it still lubricates at operating temperature and still flows at start-up. It says nothing about the absolute viscosity, which is quoted separately as the grade, nor about oxidation or pour point.
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State whether the following is true or false.
Lubricating oil base stocks are produced from the vacuum distillate fractions.
Answer: A
Solvent extraction, dewaxing and hydrofinishing convert selected vacuum cuts into base oils of the required viscosity and index. Additives then make up perhaps a fifth of a finished engine oil. Dewaxing sets the low temperature performance.
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Consider the following statements about refinery hydrogen.
1. Catalytic reforming is a significant source of it.
2. Hydrotreating and hydrocracking are large consumers.
3. Most refineries have a surplus of hydrogen.
Answer: B
The first two are correct. The third is generally false today, since tightening fuel specifications have made most refineries net importers or builders of dedicated steam reforming units. Sulphur limits drove the change over two decades.
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