PPSC Chemistry Lecturer Preparation (Test # 23)- Malik Xufyan
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PPSC Chemistry Lecturer Preparation (Test # 23)- Malik Xufyan 03137355727
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PPSC Chemistry Lecturer Preparation (Test # 23)- Malik Xufyan
- 1. Malik Xufyan WhatsApp # 0313-7355727 1| P a g e PPSC CHEMISTRY CLASS Test Session Chapter: Modern Materials Test No. 23 For more WhatsApp # 0313-7355727 Topics: 1- Polymers 2- Semi-Conductors 3. Composites 4. Liquid Crystals Polymers 1. Which of the following polymer type is not classified on the basis of its application and properties? a) rubbers b) plastics c) fibres d) synthetic 2. Which of the following is a thermosetting polymer? a) polystyrene b) polyolefins c) nylons d) phenolic resins 3. The characteristics of condensation polymerization are given below- I. only −C−C− linkages present in the polymer structure II. use of bifunctional or polyfunctional monomers III. elimination of a small byproduct molecule Which of the following is true? a) I, II, III
- 2. Malik Xufyan WhatsApp # 0313-7355727 2| P a g e b) II and III c) I and II d) Only III 4. Which of the following monomers are unsuitable for condensation polymerization? a) propanoic acid and ethanol b) butane-dioic acid and glycol c) diamines and dicarboxylic acids d) hydroxy acids 5. Which of the following is true for the resultant polymer product formed, when molecules of pthalic acid react with molecules of glycerol? a) branch polymer b) cross-link polymer c) linear polymer d) none of the mentioned 6. Which among the following polymers have lowest solubillty? a) polyethylene b) polystyrene c) nylon 6 d) epoxy resin 7. Which of the following polymer exhibit a lower value of molar cohesion? a) wool b) silk c) vulcanized rubber d) polystyrene 8. What is the range of tensile strength, exhibited by fibres? a) 300-3,000 b) 4,000-15,000 c) 20,000-150,000 d) 5,000-10,000 9. Which of the following kind of polymers are known for their high crystallinity? a) isotactic b) syndiotactic c) atactic d) none of the mentioned
- 3. Malik Xufyan WhatsApp # 0313-7355727 3| P a g e 10. Which of the following category does cellulose nitrate fall into? a) natural b) synthetic c) semi-synthetic d) none of the mentioned 11. Consider a reaction of polymer formation by condensation polymerization, completed in n-steps, with the liberation of a certain byproduct. How many total molecules of byproduct are released as a result of complete reaction? a) n+1 b) n c) n-1 d) n/2 12. How many molecules of hydrochloric acid are released when n monomers of di-acid chloride and n monomers of di-alcohol are reacted to form a polymer? a) 2n b) n-1 c) 2n-1 d) n 13. Which of the byproduct molecule is released in the formation of polyurea? a) NH3 b) H2O c) Hcl d) no elimination 14. Which of the following byproduct is released when an amine reacts with acid chloride? a) Hcl b) H2O c) NH3 d) no elimination 15. Which of the following byproduct is released when an ester reacts with alcohol? a) alcohol b) water c) ether d) no elimination 16. Which of the following reactants react to give amidation reaction?
- 4. Malik Xufyan WhatsApp # 0313-7355727 4| P a g e a) amine and acid b) amine and alcohol c) amine and ester d) ester and alcohol 17. Which of the following does not result in the formation of an ester? a) acid and alcohol b) acid chloride and alcohol c) ester and alcohol d) amine and acid 18. Consider the following statements for condensation polymerization- I. Bifunctional or polyfunctional monomers II. Loss of each kind of functional group in each step for bifunctional species III. Always accompanied by the release of a byproduct molecule IV. Monofunctional or polyfunctional monomers Which of the following are true? a) I and II b) I, II and III c) I and III d) III and IV Semi Conductor 19. How does a semiconductor behave at absolute zero? a) Conductor b) Insulator c) Semiconductor d) Protection device 20. Semiconductor acts as an insulator in the presence of impurities. a) True b) False 21. How is the resistance of semiconductor classified? a) High resistance b) Positive temperature co-efficient c) Negative temperature co-efficient d) Low resistance
- 5. Malik Xufyan WhatsApp # 0313-7355727 5| P a g e 22. What are the charge carriers in semiconductors? a) Electrons and holes b) Electrons c) Holes d) Charges 23. Which of the following is known as indirect band gap semiconductors? a) Germanium b) Nickel c) Platinum d) Carbon 24. Which column elements are combined to make compound semiconductors? a) First and fourth b) Fifth and sixth c) Second and fourth d) Third and fifth 25. Compound semiconductors are also known as direct band gap semiconductors. a) True b) False View Answer 26. How are charge carriers produced in intrinsic semiconductors? a) By pure atoms b) By electrons c) By impure atoms d) By holes 27. What type of material is obtained when an intrinsic semiconductor is doped with pentavalent impurity? a) N-type semiconductor b) Extrinsic semiconductor c) P-type semiconductor d) Insulator 28. What type of material is obtained when an intrinsic semiconductor is doped with trivalent impurity? a) Extrinsic semiconductor b) Insulator
- 6. Malik Xufyan WhatsApp # 0313-7355727 6| P a g e c) N-type semiconductor d) P-type semiconductor 29. Which method can be used to distinguish between the two types of carriers? a) Hall effect b) Rayleigh method c) Doppler effect d) Fermi effect 30. For semiconductors, the resistivity is inversely proportional to the temperature for semiconducting materials. a) True b) False Liquid Crystal 31. The full form of LCD is ____________ a) Liquid Crystal Display b) Liquid Crystalline Display c) Logical Crystal Display d) Logical Crystalline Display 32. The optical properties of liquid crystals depend on the direction of ___________ a) Air b) Solid c) Light d) Water 33. By which properties, the orientation of molecules in a layer of liquid crystals can be changed? a) Magnetic field b) Electric field c) Electromagnetic field d) Gallois field 34. Electro-optical effect is produced in ___________ a) LED b) LCD c) OFC
- 7. Malik Xufyan WhatsApp # 0313-7355727 7| P a g e d) OLED 35. The direction of electric field in an LCD is determined by ___________ a) the molecule’s chemical structure b) Crystalline surface structure c) Molecular Orbital Theory d) Quantum Cellular Automata 36. The first LCDs became commercially available in ___________ a) 1950s b) 1980s c) 1960s d) 1970s 37. LCDs operate from a voltage ranges from ___________ a) 3 to 15V b) 10 to 15V c) 10V d) 5V 38. LCDs operate from a frequency ranges from ___________ a) 10Hz to 60Hz b) 50Hz to 70Hz c) 30Hz to 60Hz d) None of the Mentioned 39. In 7 segment display, how many LEDs are used? a) 8 b) 7 c) 10 d) 9 40. What is the backplane in LCD? a) The ac voltage applied between segment and a common element b) The dc voltage applied between segment and a common element c) The amount of power consumed d) For adjusting the intensity of the LCD Composites
- 8. Malik Xufyan WhatsApp # 0313-7355727 8| P a g e 41. Composites can be classified based on ___________ a) matrix type b) reinforcement constituent c) matrix type & Reinforcement constituent d) neither on matrix type nor on reinforcement constituent type 42. Which of the following is not a laminar composite? a) Bimetallic b) Cladding c) Paints d) Wood 43. The composite constituents of both matrix and reinforcements are softer. a) True b) False 44. In sandwich composites, which of the following material can be used for filling purpose? a) Wood b) Cement c) Polymer d) All of the mentioned 45. Which of the following have a greater impact on longitudinal strength of reinforced composites? a) Fiber orientation b) Fiber strength c) Fiber length d) Fiber diameter 46. Which of the following may alter the mechanical properties of reinforced composites? a) Constituent properties b) Fiber length c) Fiber orientation d) All of the mentioned 47. Which of the following property can be enhanced by reinforcing an aluminum alloy? a) Density b) Torsion resistance c) Wear resistance d) Strength
- 9. Malik Xufyan WhatsApp # 0313-7355727 9| P a g e 48. Which of the following is the correct size range of dispersoids (in micrometres) in dispersion strengthened composites? a) 0.0001-0.0009 b) 0.01-0.1 c) 0.1-1.0 d) 2.0-2.7 49. Which of the following is correct dimensional of flake composites? a) 1-Dimensional b) 2-Dimensional c) 3-Dimensional d) 4-Dimensional 50. Fire point of composite is high. a) True b) False