Applied Chemistry Interview Questions and Answers for freshers focuses on “Classification of Lubricants – 3”.
1. Lubricating oil thickened with metallic soaps or by adding solid forms __________
a) grease
b) vaselines
c) oils
d) petrol
Answer: a
Clarification: Grease is made from lubricating oil with metallic soaps or by adding solids like graphite, silica, talc etc. The petroleum oil they are not very simply lubricating oils, they are the lubricating oils thickener is dispersed to produce gel.
2. Stabilized erosion of the fine solid particles in liquid is called ___________
a) colloidal suspension
b) molecular suspension
c) colloidal dispersion
d) molecular dispersion
Answer: c
Clarification: Stabilized erosion of the fine solid particles in liquid is called molecular dispersion. When the molecular dispersion is takes place and then the lubricating oil started to show the characteristics and behaviour of the solid then it is said to be gel.
3. 99% of grease is produced from __________
a) petroleum oil
b) olive oil
c) castor oil
d) whale oil
Answer: a
Clarification: The semi-solid lubricants are generally made by incorporation of the lubricating oil with metallic soap to the liquid lubricants. 99% of the grease is produced from the petroleum oil. Olive oil, castor oil and whale oil are the types of liquid lubricants.
4. The more friction of the greases is due to their high __________
a) velocity
b) viscosity
c) temperature coefficient
d) buoyancy
Answer: b
Clarification: The more friction of the greases is due to their viscosity. They are very thick semi solid lubricants. If the speed in high then friction is also high and then the heat produced will be more. As, the greases are very poor coolants they will be overheated.
5. Slaked lime solution is mixed with tallow oil with constant stirring to produced ______________
a) solution base greases
b) cup greases
c) complex greases
d) lithium base greases
Answer: b
Clarification: Cup greases are produced by mixing the slaked lime solution with the tallow oil with constant stirring at hot condition. After soap formation is complete petroleum is added to it and mixed. Some amount of water is generally mixed with greases.
6. Calcium complex grease can be made from ___________
a) lime, fatty acid, acetic acid
b) calcium, lime, acetic acid
c) calcium, lime, acetic acid
d) lime, calcium, acetic acid
Answer: a
Clarification: Calcium complex grease is formed out of the lime, fatty acid and acetic acid. The grease can be formed by using the sodium, aluminium and lithium. That is why these lubricants have high melting points.
7. Complex grease fibers are formed by reacting two dissimilar ___________ with single _________
a) base, alkali
b) alkali, acids
c) alkali, base
d) acids, alkali
Answer: d
Clarification: Complex grease fibers are formed by reacting two dissimilar acids with single alkali that are used as thickener in many of the commercial complex greases. Additives like anti-oxidants, corrosion inhibitors and extreme pressure additives are added to the greases.
8. Lithium soap greases are __________
a) temperature resistant
b) fire resistant
c) water resistant
d) pressure resistant
Answer: c
Clarification: Lithium soap greases are the water resistant as they have combined advantages of the both calcium base greases and sodium base greases. They can be used at high temperatures. These properties of these lubricants are responsible for their use in wide range.
9. High mechanical stability is more for ________
a) sodium base greases
b) lithium soap greases
c) complex greases
d) cup greases
Answer: b
Clarification: About 65% of the market is captured by the lithium greases. They have high mechanical stability. They are also stable for storage. They are expensive and used for specific applications like in air crafts.
10. Sodium base greases can be utilized up to the temperature of ____________
a) 175oC
b) 100oC
c) 75oC
d) 80oC
Answer: a
Clarification: Sodium soaps are soluble in water and they are not water resistant. As they are not stabilized with water. They can resist up to a temperature of 175oC. They can be used at ball and roller bearing at which there will be heat production due to heat.
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