This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Adhesives, their Advantages and Limitations”.
1. The substances which are capable of uniting two other materials together by adhering strongly to the surface of both are called ____________
a) Organic conducting polymers
b) Biodegradable polymers
c) Adhesives
d) Composites
View Answer
Explanation: The substances which are capable of uniting two other materials together by adhering strongly to the surface of both are called adhesives. Adhesives may be found naturally or produced synthetically.
2. Select the incorrect statement from the following option.
a) Two surfaces are rapidly, economically and easily joined to each other by adhesives
b) The process of applying adhesives requires highly specialized workers or high heat
c) Adhesives bonding requires less after-finishing
d) Bonding by adhesives gives smoother finished surfaces
View Answer
Explanation: The process of applying adhesives does not require highly specialized workers or high heat. All the other options are correct.
3. Corrosion of metals at the joints is minimized by joining dissimilar metals with adhesives because ____________
a) Direct metal to metal contact is avoided
b) Adhesive act as a lubricator at the joints
c) Metals are covered with adhesives
d) Adhesives prevent the exposure to environment
View Answer
Explanation: Corrosion of metals at the joints is minimized by joining dissimilar metals with adhesives because direct metal to metal contact is avoided so galvanic action is reduced.
4. Adhesives joints are leak-proof for ____________
a) Solids only
b) Liquids only
c) Gases only
d) Both liquids and gases
View Answer
Explanation: Adhesives joints are leak-proof for liquids and gases. There is no leaking of solids.
5. Joining of labels to plastic cans or bottles is not possible without the use of adhesives.
a) True
b) False
View Answer
Explanation: Joining of labels to plastic cans or bottles is not possible without the use of adhesives. Adhesives are typically organized by the method of adhesion.
6. The strength of adhesive joint is _____________ than mechanical joint obtained by welding or riveting.
a) More
b) Less
c) Equals to
d) Very less
View Answer
Explanation: The strength of adhesive joint is less than mechanical joint obtained by welding or riveting. Mechanical joints are permanent and stronger as they are joined with the help of nuts and bolts.
7. On increasing the temperature, the strength of adhesive ____________
a) Remain same
b) Increases
c) Decreases
d) First increases than decreases
View Answer
Explanation: On increasing the temperature, the strength of adhesive decreases due to relative weakness in bonding large objects with a small bonding surface area and greater difficulty in separating objects during testing.
8. The bond energy of a metallic bond is ____________
a) 600-1200 kJ/mol
b) 60 kJ/mol
c) 20 kJ/mol
d) 100-350 kJ/mol
View Answer
Explanation: The bond energy of a metallic bond is 100-350 kJ/mol. Metallic bonding is the force of attraction between valence electrons and metal ions. Therefore, it is very strong in nature.
9. Which of the following is not an example of thermosetting synthetic resins?
a) Epoxy
b) Acrylic polyester
c) Cellulose derivatives
d) Silicones
View Answer
Explanation: Epoxy, silicones, acrylic polyester, polyurethane etc are some of the examples of thermosetting synthetic resins.
10. Which of the following adhesive is prone to brittle failure?
a) Acrylic polyester
b) PF resin
c) UF resin
d) Epoxy
View Answer
Explanation: PF resins are prone to brittle failure due to its tough structure.
11. The epoxy resins are the _______________ products of epichlorohydrin and bisphenol.
a) Free radical
b) Addition
c) Ion-exchange
d) Condensation
View Answer
Explanation: The epoxy resins are the condensation products of epichlorohydrin and bisphenol. They are formed by the condensation reaction.
12. Epoxies are used in wide diversity of applications because of their strength, durability and great versatility.
a) True
b) False
View Answer
Explanation: Epoxies are used in a wide diversity of applications because of their strength, durability and great versatility. Epoxy resins are low molecular weight pre-polymers or higher molecular weight polymers which normally contain at least two epoxide groups. The epoxide group is also sometimes referred to as a glycidyl or oxirane group.
13. Which of the following is used as curtain-wall sealants?
a) Polyurethane
b) Silicones
c) Polyvinyls
d) Cellulose derivatives
View Answer
Explanation: Although expensive, silicones are used as curtain-wall sealants because of their excellent aging characteristics.
14. Emulsion adhesives are based on ____________
a) Polyurethane
b) Collodion
c) Urea-formaldehyde
d) Polyvinyl acetate
View Answer
Explanation: Emulsion adhesives are based on polyvinyl acetate. It is formed by the emulsification and polymerization of acetic vinyl, EVA and acrylic resin in water.
15. Collodion is a mixture of cellulose nitrate with ____________
a) Alcohol
b) Ketone
c) Carboxylic acid
d) Phenol
View Answer
Explanation: Collodion is a mixture of cellulose nitrate with alcohol. It is a flammable, syrupy solution.
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