1. 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.
2. On cooling below the pour point, the wax will be __________
a) Evaporated
b) Condensed
c) Crystallized
d) Sublimated
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.
3. 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.
4. Gear oils on adding viscosity index improves can be used in ___________
a) Motor vehicles
b) Machinery
c) Air crafts
d) Engines
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.
5. Foaming of oils can be prevented by using ___________
a) Despersants
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.
6. vegetable oils are added to the lubricants to improve their ___________
a) Lubrication
b) Oiliness
c) Viscosity
d) Efficiency
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.
7. Viscosity means the flow of the liquid is resisted by ________
a) Itself
b) Other liquid
c) Water
d) Alcohol
Explanation: The viscosity of the liquid is defined as the resistance offered by the liquid for its own flow. The viscosity is more for the fluids having more density. The flow of one layer of the liquid is actually opposed by the other layer of the same liquid.
8. The viscosity of an oil decrease when temperature ________
a) Decreases
b) Is constant
c) Increases
d) 100oC
Explanation: The viscosity of an oil decreases with an increase of the temperature. In internal combustion engines and aeroplanes, the engine must start at low temperature and as well they must be operated at high temperatures. So, the viscosity of an oil must be moderate.
9. The rate of change of the viscosity with raise in temperature is measured by an arbitrary scale called as _________
a) Arbitrary constant
b) Viscosity constant
c) Viscosity index
d) Arbitrary index
Explanation: The rate of the change of the viscosity with raise in temperature is measured by an arbitrary scale called as viscosity index. The viscosity index is found by comparing the viscosity of the oil under the temperature of 1000F with two standard oils.
10. Mathematically, viscosity index can be given by __________
a) {(L+U)/(L-H)}*100
b) {(L -U)/(L+H)}*100
c) {(L+U)/(L+H)}*100
d) {(L -U)/(L-H)}*100
Explanation: The viscosity index can be given by {(L -U)/(L-H)}*100. Here, the U=viscosity at 100F oil under the test. V=viscosity at 100F of standard coast oil having V.I zero. H=viscosity at 100F of pennsylvanian crude oil having V.I 100