This set of Applied Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Types of Additives”.
1. The most common reason for the degradation of petroleum oil is their _________
d) Temperature coefficient
Explanation: Oxidation inhibitors are one of the types of the additives. The oxidation is the main reason for the petroleum oil degradation. At high temperatures, the hydro carbons of the petroleum oil undergo homolytic fission to generate free radicals.
2. The oxidation inhibitors terminate the hydro peroxide chain by combining with ___________
a) Hydrogen peroxide
b) Oxides of metals
c) Hydro carbons
Explanation: After the homolytic fission of the petroleum oil to produce free radicals and they react with oxides to form the hydrogen peroxides. Some hydro peroxides decompose to form the aldehydes, ketones etc. If they are reacted with hydrogen peroxide then the chain will be terminated.
3. ___________ are surface active additives.
a) Oxide inhibitors
b) Rust inhibitors
d) Friction modifiers
Explanation: The rust inhibitors are the surface active additives. They mainly acts on the surface and makes the metal corrosion free. Mainly from the water corrosion. They form thin film on the surface. It is the oxide film that protects the metal.
4. Tiadiazole and triazole derivatives are used for __________
a) Aluminium alloy corrosion
b) Silver corrosion
c) Copper corrosion
d) Manganese corrosion
Explanation: The tiadiazole and triazole derivatives are used to protect the non ferrous metals from corrosion. They also protect the copper derivatives from corrosion. Organic phosphates and sodium and sodium and calcium sulphonates are used as the rust inhibitors in machinery.
5. To reduce the wear and tear of the gears ____________ are used.
a) Anti wear agents
b) Rust inhibitors
c) Oxide inhibitors
Explanation: To reduce thee wear and tear of the gears anti wear agents or the extreme pressure agents are used. In high pressure hydraulic components are zinc dialkyl dithiosulphates are used.
6. In steel and steel lubrication, the zinc dialkyl dithiosulphates forms __________
Explanation: In steel and steel lubrication, the zinc dithiosulphates forms the zinc oxide, zinc sulphide and ferrous oxide and some other zinc organo phosphates. They prevent the wear and tear of steel.
7. In automotive applications __________ are used.
a) Friction modifiers
c) Anti wear agents
d) Oxide inhibitors
Explanation: The friction modifiers are used in the auto mobile applications. Mild extreme pressure agent in boundary lubrication conditions are, they prevent stick slip oscillations and control noise in the automatic transmissions.
8. Friction modifiers have 12-18 carbons.
Explanation: The friction modifiers have 12 to 18 carbons. The fatty alcohols and esters of fatty acids also act as friction modifiers. Glyceride of the rapeseed and lard oil is used as the friction modifiers in machineries.
9. The oil insoluble sludge can be reduced by using ____________
a) Pour point depressants
b) Friction modifiers
c) Oxide inhibitors
Explanation: The oil insoluble sludge can be reduced by using detergents. Despersants are similar to detergents. Vanish and carbon from fuel combustion in internal combustion engines, there will be depositions of oil insoluble materials. Those are reduced by detergents.
10. The commonly used dispersant is _____________
a) Carboxylic acid
b) Alkyl phosphoric acid
c) Poly butyl succinic acid
d) Sodium salts of alkyl benzene sulfonic acid
Explanation: The calcium, sodium and magnesium salts of the alkyl benzene sulfonic acids are used as detergents. Carboxylic aids and the alkyl phosphoric acid are the other commonly used detergents. The commonly used despersants is poly butyl succinic acid.
11. On cooling below the pour point, the wax will be __________
Explanation: On cooling below the pour point, the wax will be crystallized and the additive molecules will protect them from crystallization as they will be adsorbed on the surfaces of the crystals.
12. The viscosity index can be improved by adding ___________
a) Linear polymers
b) Branched polymers
c) Cyclic polymers
d) Inorganic materials
Explanation: The viscosity index can be improved by adding linear polymers like poly isobutyls and poly methacrylates and poly alkyl styrene. They range from 10000 to 100000 molecular weight. They increase the viscosity and retains the original viscosity coefficient.
13. Gear oils on adding viscosity index improves can be used in ___________
a) Motor vehicles
c) Air crafts
Explanation: Gear oils on improving the viscosity, they can be used in air crafts. There are some other materials that can be used in air crafts by increasing their viscosity are multi grade automotive engine oils and automatic transmission oils.
14. Foaming of oils can be prevented by using ___________
b) Foam inhibitors
c) Rust inhibitors
d) Oxide inhibitors
Explanation: Foam inhibitors are used for preventing the foaming of oil in internal combustion engines. Methyl silicone polymers are used as effective foam inhibitors.they are not soluble in oil they help in breaking form bubbles.
15. vegetable oils are added to the lubricants to improve their ___________
Explanation: Oiliness can be improved by adding vegetable oils, castor oils and olive oil to the lubricants. The compounds having strong polar groups like dibenzyl dilsulphide, amyl phenyl phosphate are used as oiliness improvers.
Sanfoundry Global Education & Learning Series – Applied Chemistry.
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