506. What causes the foul smell of the rancid butter?
507. Which compound of silver is used in the silvering of mirrors?
508. What are examples of natural polymers?
Cellulose, starch, rubber, wool & silk
509. What are the examples of synthetic polymers?
Polythene, nylon, dacron & Orion
510. The polymers soften on heating and become hard on cooling & can be remoulded, recast and reshaped are known as—–
511. The polymers that can only be moulded into the desired shape on heating once & cannot be reused are known as——
512. Which is the semi-synthetic polymer obtained by chemical treatment of the wood pulp (cellulose)?
513. What is known as Artificial silk’?
514. What is the type of polymerisation in which simple monomers are united together without loss of small molecules?
515. Name the important addition of polymers?
Polythene, Teflon, Thermocol, polypropylene, Orion & carbon fibres
516. Which type of polymer is obtained by polymerisation of ethylene?
517. Which polymer is used in the insulation wires and manufacturing of squeeze bottles, toys, flexible pipes and buckets?
518. Which type of polymer is obtained by the polymerization of tetrafluoroethylene?
519. Which type of polymer is used as a substitute for wool in making commercial fibres?
520. Which type of polymer is used in indoor/outdoor carpeting and upholstery?
521. Which type of polymers is stronger than steel, stiffer than titanium and lighter than aluminium?
522. Which type of polymer is used in the defence sector as nose tips and head shields of missiles?
523. What are the examples of condensation polymers?
Bakelite, Glyptal, Nylon
524. In which type of polymerisation is simple monomers are joined together with loss of small molecules like water & ammonia?
525. What is obtained by the condensation polymerisation of phenol and formaldehyde?
526. The natural rubber is a linear polymer of?
Isoprene (2-methyl-l, 3-butadiene)
527. The natural rubber is obtained from the —-of the rubber tree?
528. Who discovered the synthetic rubber?
Mathews & Harris
529. What are the examples of the synthetic rubber?
Thiokol, Neoprene, Buna-N & Buna-S
530. Which synthetic rubber has a superior re¬sistance to vegetable and mineral oils?
531. Which synthetic rubber is used for manufacturing conveyor belts, hoses & gaskets?
532. Which synthetic rubber is resistant to the action of petrol, lubricating oils & organic solvents?
533. Which synthetic rubber is used in making oil seals, tank lining etc?
534. Which synthetic rubber is also known as SBR?
535. Which synthetic rubber is used in the manufacturing of automobile tyres & rubber soles?
536. Which acid is used for coagulating the latex?
537. What should be the percentage of dilution of formic acid before it is added to latex?
538. The heating of rubber with sulphur is known as ——?
539. Why rubber is vulcanised?
To make rubber hard, strong & more elastic
540. What is the name of the mixture of calcium cyanamide & carbon?