Chemistry M.C.Q (1 Marks)

Neoprene has superior resistance to vegetable and mineral oils.
The material used in the neoprene is nothing but the rubber which has strong resistant towards vegetable and mineral oil.

Teflon and polystyrene are thermoplastics since they can be moulded again by heating and melting.

The polymer of ethylene glycol and terephthalic acid is known as terylene or dacron.

Blended fibres are made by combining various fibres to enhance the property of the product.
For eg: spandex and cotton is a natural mix for sports clothing and undergarments to improve stretching properties and prevent odour.
A blended fabric helps overcome the disadvantages of natural and synthetic fibre.

Copolymerisation is a polymerization reaction in which a mixture of more than one monomeric species is allowed to polymerize to form a copolymer.

Dacron, also known as Terylene; a polymer formed from polymerization of ethylene glycol and Terephthalic acid.

Cellulose, protein and starch are classified as natural polymers. They are obtained from either plants or animals.
They are named as plant polymers and animal polymers.
Other examples of natural polymers include jute, linen, silk and wool etc.
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Polymerisation is the joining together of two or more simple molecules called Monomers to form a new compound of the same empirical formula called a polymer which has higher molecular weight.

Neoprene polymerizes from its monomer unit chloroprene.

Nylon is the strongest man-made fiber prepared by polymerizing amide molecules.
Nylon is used in the making of different types of clothes, ropes, sleeping bags, parachutes, tents etc because the fiber of nylon is stronger than a steel wire of the same thickness.

The addition polymers are formed by the repeated addition of monomer molecules possessing double or triple bonds, e.g., the formation of polythene from ethene and polypropene from propene. However, the addition polymers formed by the polymerisation of a single monomeric species are known as homopolymers.

Polymer used to make gasket of pressure cooker is teflon. Teflon is formed by free radical vinyl polymerisation of the monomer tetrafluoroethylene.

Polyamides are generally fibers because of the intermolecular forces like hydrogen bonding which gives them high tensile strength.

In vulcanization, there is formation of crosslinks of sulphur at the reactive sites of the double bond which stiffens the rubber and also increase the resistance to abrasion and tensile strength, the elasticity of the rubber.

People who weave clothes are called weavers. The person makes fabric by weaving fibre. Weaving is a method of textile production consisting of two different types of thread that are interlaced at right angles to form the cloth

Bakelite is a condensation polymer of phenol and formaldehyde.
Bakelite is widely used for making molded products.
It was the first plastic made from synthetic components.

Vulcanization is addition of sulphur in natural rubber by chemical process to improve its durability.

Plastic have low toxicity due to their insolubility in water and because they are biochemically inert due to large molecular weight. Plastic products contain a variety of additives. Plastic is light, durable and doesn't react chemically with water.

Polymers are made of repeat units derived from natural gas or coal or crude oil. But building block repeat units can sometimes be made from renewable materials such as polylactic acid from corn or cellulosics from cotton linters.
Some plastics have always been made from renewable materials such as cellulose acetate used for screwdriver handles and gift ribbon.

Mixture of styrene and methyl methacrylate can form a copolymer and not an ionic addition polymer.
Hence, the statement in option is incorrect.
Other statements are correct.

Nomex is used to manufacture clothes for firefighters . It is also used to prepare protective clothes for race car drivers. Dynel is used in the preparation of human hair wigs.
Thiokol is used in rubber. Kevlar is used to prepare bullet proof vests and helmets.

Chain growth polymerization is involved in the manufacture of polymers such as polyethylene. Free radical mechanism for ethylene takes place at high temperature and pressure which can be remoulded by its repeating carbon chain.

The commercial name of polyacrylonitrile is Orion or acrilan.

Vulcanised rubber is highly elastic, so weakest intermolecular forces present in it.

Plastics are polymers formed from small molecular fragments which are known as monomers and plastic is the macromolecular fragment.
All polymers are not plastics but all plastics are polymers.

Sulphur is used for vulcanization of rubber to make it more strong, tough and elastic.
Note: Natural rubber is soft, sticky and has less tensile strength.

There is high steric regularity in isotactic polymers which fosters close packing of molecular chains. Thus, they are highly crystalline.

Dacron is obtained by the condensation polymerisation of dimethyl terephthalate and ethylene glycol.
Dacron is polyester and is also called terylene.

Carbon black is used in various formulations with different rubber types to customize the performance properties of tyres.
Different grades of carbon black are used to optimize properties like handling,tradewear, fuel mileage and abrasion resistance.

Polymers can be recycled mechanically or chemically. In land fill polymers are buried in the ground so that they do not accumulate and cause pollution. Incineration is heating at high temperature.
Heat energy released by polymers is used to generate electricity.

Bakelite is a thermosetting phenol formaldehyde resin, formed from elimination reaction of phenol with formaldehyde.

Vulcanised rubber is used in making automobile tyres and foot wear.
Heating of rubber with sulphur is called as vulcanisation. It makes the rubber hard and more flexible.

These are the polymers formed by free radical mechanisms with a random orientation of groups.

Nomex is used in protective clothing for race car drivers and firefighters.
Thiokol is used in rubber.
Saran is used in bumpers.
Glyptal used in the manufacture of paints and lacquers.

In fractional distillation of petroleum, the vapours with highest boiling point condense in lowermost portion.
As the vapors of highest boiling point evaporates later and condenses later at lower portion.

A polymer is formed by Dehydration synthesis means removal of water molecule.

Glycogen is a polymer of glucose found in lever, brain and muscles of animals.

Gutta percha is called trans-form of rubber, as it is a polymer of isoprene, the basic sub unit in natural rubber.

Rubber has isotactic stereochemistry, not syndiotactic.
Tacticity refers to the orderliness of succession of configurational repeating units in the main chain of a macromolecule.
This is an application of stereochemistry as it concerns the spatial arrangement of substituent groups.

Plexiglass is a very important commercial polymer because of its high resisting properties.
It is a polymer of methyl methacrylate.
The structure of the methylmethacrylate is given above.

Thermosetting polymers: These polymers are cross linked or heavily branched molecules, which on heating undergo extensive cross linking in moulds and again become infusible. These cannot be reused.

Proteins are natural polymers. Rest of them are synthetic polymers.

Ice is not a polymer. Whereas all the others are polymers of glucose and/or fructose.

Natural rubber latex is basically a colloidal dispersion of rubber hydrocarbon in an aqueous medium. Ammonium and potassium alums are used as a coagulant in latex.

Fibres are thread forming solids which possess high tensile strength.
Dacron is formed by the interaction of ethylene glycol and terephthalic acid.

Synthetic fibres are synthesized from a raw material called polymers.

Given polymer can be obtained condensation polymerization of ethylene glycol and phthalic acid with the elimination of water molecule.

Nylon is strong enough to bear heavy weights, extend and then regain its original shape and length, making it very resourceful in fishing nets and also durable.

Prior to rubber tires, metal and wood were the materials in use. However it was found that natural Rubber provides better cushioning, makes less noise.
Further rubber deforms under weight /force which results in larger contact patch with the road than with metal/wood tires of same diameter/width.
During cornering at high speeds, the deformation of sidewall and larger contact area improves the traction or grip on the road increasing safety.

The polymer used in making handles of cookers and frying pans is Bakelite.
It is also used in making switches, combs etc. It is phenol formaldehyde polymer.

Bakelite is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde.

Teflon is a condensation polymer.

Vulcanization is the process by which rubber molecules are cross linked with each other by heating the liquid rubber with sulphur. Crosslinking increases the strength and elasticity of rubber.
It is very elastic such that it can be stretched reversible.

Vulcanization is a chemical process of addition of sulphur.
By this method physical properties of natural rubber are improved. Finished rubber has higher tensile strength and resistance to swelling and abrasion.

Dextron is a polyacetic acid polyglycolic acid polymer. The monomers used are lactic acid and glycolic acid. It is copolymer and has ester linkage. It is used as friction modifier. It is added to lubricants to reduce surface friction.

Polystyrene is used to make disposal plastic such as thermocol.
 

Acetaldehyde is primarily used as an intermediate in the manufacture of a range of chemicals, perfumes, aniline dyes, plastic and synthetic rubber, etc.

Synthetic rubber is more resistant to acids, oils, heat, aging and has more strength than natural rubber.

Vulcanization is a chemical process by which the physical properties of natural or synthetic rubber are improved. In its simplest form, vulcanization is brought about by heating rubber with sulfur.

Bakelite is formed by condensation reaction of phenol with formaldehyde, i.e., methanal.

The polymerization of ethene to polythene consists of heating or exposing to light, a mixture of ethene with a small amount of benzoyl peroxide initiator.

The structure of cross linked polymer, Bakelite is shown above. It is formed by condensation polymerization of Phenol and formaldehyde monomers.

Vulcanization is the of heating natural rubber with sulphur in order to develop some specific qualities such as abrasion resistance, heat resistance and elasticity.
Hence, it is an incorrect statement.