Applied Chemistry Multiple Choice Questions on “Natural Rubber”.
1. The polymers which possess the property of elastic is called rubber.
a) True
b) False
Answer: a
Clarification: The polymers which possess the property of elastic is called the rubber. Temporary deformation takes place.
2. The temporary deformation of rubber takes place after applying the _______ stress.
a) 600e.u
b) More than 600e.u
c) 500e.u
d) more than 500e.u
Answer: b
Clarification: The temporary deformation of the rubber takes place after applying the stress around more than 600e.u. when the stress is applied the chains get partially aligns with respect to the other.
3. The elasticity of the rubber is due to its ___________
a) Trigonal planar
b) Octahedral
c) Pentagonal bipyramidal
d) Helix
Answer: d
Clarification: The elasticity of the rubber is due to its helical structure. On releasing the stress, the chains get reverted back to their original coiled state.
4. Isoprene in natural rubber exists in ___________ geometrical isomeric forms.
a) 2
b) 3
c) 4
d) 5
Answer: a
Clarification: Isoprene in natural rubber exists in two geometrical isomeric forms. They are cis-isoprene and trans-isoprene.
5. Cis-poly isoprene is present in ________
a) Hevea rubber
b) Guayule rubber
c) Percha rubber
d) Gutta rubber
Answer: a
Clarification: Cis-poly isoprene is present in the Hevea rubber and the trans-poly isoprene is present in guayule rubber and percha rubber.
6. The latex is diluted to _________ and filtered to remove suspended impurities.
a) 5-10%
b) 10-15%
c) 15-20%
d) 20-25%
Answer: c
Clarification: The latex is diluted to 15-20% and filtered to remove suspended impurities like pieces of bark, leaves etc.
7. The filtered latex is sent into the tanks and treated with __________
a) Acetic acid
b) Formaldehyde
c) Acetaldehyde
d) Poly isoprene
Answer: a
Clarification: The filtered latex is sent into the tanks and treated with the acetic acid. Instead of acetic acid, sometimes we can also use the formic acid.
8. The rubber coagulates into soft _________ colour mass.
a) Yellow
b) Light yellow
c) White
d) Light pink
Answer: c
Clarification: The rubber coagulates into soft white colour mass which is called as coagulam and then filtered and washed with water.
9. While producing the crepe rubber, the coagulam is passed between two rollers of about _________ wide.
a) 3mm
b) 4mm
c) 50cm
d) 100cm
Answer: c
Clarification: The coagulam is passed in between the two rollers of about 3mm apart and 50cm wide and extruded in the form of a sheet which resemble the crepe paper, which possess rough surface.
10. While producing the smoked rubber, the filtered latex is fed into long rectangular tanks of _________ deep.
a) 1m
b) 2m
c) 50cm
d) 30cm
Answer: d
Clarification: In one type of processing the filtered latex is fed into long rectangular tanks of 30cm deep and 1m wide.
11. While producing smoked rubber, the latex and reacted with formic acid, the vertical partition plates are inserted and left undisturbed for _________
a) 13 hours
b) 14 hours
c) 15 hours
d) 16 hours
Answer: d
Clarification: After introducing the latex and reacted with formic acid, the vertical partition plates are inserted and left undisturbed for 16 hours.
12. While producing the smoked rubber, the sheets are hanged for about _________ in smoked chambers.
a) 1 day
b) 2 days
c) 3 days
d) 4 days
Answer: d
Clarification: While producing the smoked rubber, the sheets are hanged for about 4 days in smoked chambers. The final roller gives ribbed pattern to the rubber sheet.
13. To produce the smoked rubber, the rubber sheets are hanged in smoked chambers at __________
a) 10-20oC
b) 20-30oC
c) 30-40oC
d) 40-50oC
Answer: d
Clarification: To produce the smoked rubber, the rubber sheets are hanged in smoked chambers at 40-50oC for four days.
14. Solvent extraction process is used to extract __________
a) Crepe rubber
b) Smoked rubber
c) Gutta percha
d) Guayule rubber
Answer: c
Clarification: Solvent extraction process is the method of extracting the gutta percha. It is extracted from the matured leaves of the palagum gutta and dichopsis gutta.
15. In solvent extraction process, the mature leaves are grounded and heated about _________
a) 40oC
b) 50oC
c) 60oC
d) 70oC
Answer: d
Clarification: In solvent extraction process, the mature leaves are grounded and heated about 70oC. It is heated along with water.