Polymers

All the given statements are correct i.e. $A, B, C$.

Glyptal is made from monomer ethylene glycol and phthalic acid.

• Bakelite is used in making combs, phonograph records, electrical switches and handles of utensils etc.

• Nylon-2-nylon-6 is an alternating polyamide copolymer of glycine and amino caproic acid.

It is a biodegradable polymer.

$ \begin{aligned} &\text { Weight average molecular mass }\\ &\begin{aligned} & \left(\bar{M}_w\right)=\frac{\Sigma n_i m_i^2}{\Sigma n_i m_i} \\ & =\frac{3 \times\left(10^3\right)^2+3 \times(500)^2+4 \times(200)^2}{3 \times 10^3+3 \times 500+4 \times 200} \\ & =\frac{3,000,000+7,50,000+1,60,000}{5300} \\ & =737.7 \end{aligned} \end{aligned} $

The correct match is A-III, B-I, C-IV, D-II.

Bakelite is a polymer made up of monomers, phenol and formaldehyde.

Natural rubber is a polymer made up of monomers 2 -methyl-1,3-butadiene.

Glyptal is formed from monomeric units phthalic acid and ethylene glycol.

Nylon-2-nylon-6 is formed from glycine and aminocaproic acid monomers.

Let's analyze the list one by one to identify which ones are elastomers:

$\textbf{Natural rubber}$ – It is a classic elastomer, mainly composed of cis-1,4-polyisoprene.

$\textbf{Polyethene}$ – This is a thermoplastic polymer, not known for rubber-like elasticity.

$\textbf{Vulcanized rubber}$ – Vulcanization is a process applied to rubber (often natural rubber) to enhance its elasticity and strength, so it remains an elastomer.

$\textbf{Bakelite}$ – This is a thermosetting plastic, not an elastomer.

$\textbf{Polyvinylchloride (PVC)}$ – Typically a thermoplastic, it does not exhibit the high elasticity characteristic of elastomers.

$\textbf{Buna-N}$ – Also known as nitrile rubber, it is a synthetic elastomer commonly used for its oil resistance.

$\textbf{Nylon-6}$ – A polyamide that is a thermoplastic, not classified as an elastomer.

$\textbf{Neoprene}$ – Another synthetic rubber well known for its elastic properties, making it an elastomer.

From the list, the elastomers are:

Natural rubber

Vulcanized rubber

Buna-N

Neoprene

Thus, there are 4 elastomers.

The correct answer is: Option A (4).

A cross-linked polymer is a type of polymer where the individual polymer chains are linked together by covalent bonds, forming a three-dimensional network. This cross-linking process significantly affects the properties of the polymer, making it more rigid, durable, and resistant to heat and chemicals.

Let's evaluate the given options:

Option A: Teflon

Teflon is a brand name for a polymer called polytetrafluoroethylene (PTFE). It is not a cross-linked polymer; rather, it consists of linear chains without cross-linking.

Option B: Polythene

Polythene or polyethylene is a polymer made from ethylene monomers. It can be either low-density polyethylene (LDPE), which has some branching, or high-density polyethylene (HDPE), which is mostly linear. Neither form is typically cross-linked.

Option C: Nylon

Nylon is a type of synthetic polymer, specifically a polyamide. Nylon polymers are generally linear and not cross-linked.

Option D: Bakelite

Bakelite is a type of phenol-formaldehyde resin, which is a thermosetting polymer. Thermosetting polymers are known for their heavily cross-linked structures. Bakelite forms an extensive, three-dimensional network through cross-linking, which makes it very hard and heat-resistant.

Therefore, the correct answer is:

Option D: Bakelite

Starch, Protein, Rubber are natural polymer.

Rayon is a semi-synthetic fiber, made from natural sources of regenerated cellulose, such as wood and related agricultural products.

Melamine polymer is formed by the condensation polymerization of melamine and formaldehyde.

Buna – N is synthetic rubber which can be stretched and retains its original status on releasing the force.

A copolymer is a polymer that consists of two or more different types of monomers.

Here are the options examined:

• Option A: Buna-S - It's a copolymer of butadiene and styrene.


• Option B: Neoprene - It is made from the polymerization of chloroprene, so it is a homopolymer, not a copolymer.


• Option C: PHBV - Polyhydroxybutyrate-co-valerate (PHBV) is a copolymer consisting of Polyhydroxybutyrate (PHB) and Polyhydroxyvalerate (PHV).


• Option D: Butadiene-styrene - This is another name for SBR, or styrene-butadiene rubber, and it's a copolymer of butadiene and styrene.

Therefore, the correct option is (A).

(A) Polymerization of chloroprene gives synthetic rubber.

(B) Teflon is manufactured by heating tetrafluoroethene with a free radical or persulphate catalyst at hight pressure.

(C) Polyvinyl chloride (PVC) is a thermoplastic polymer and used in making hand bags, vinyl flooring and water pipes.

(D) Ethene at 350-570 K temperature and 1000-2000 atm pressure in the presence of a peroxide initiator yields low density polythene.

Preparation of polyethylene is done in the presence of the "Zeigler-Natta catalyst" which is a mixture of trimethylaluminium $\left[\mathrm{Al}\left(\mathrm{CH}_3\right)_3\right]$ and titanium tetrachloride $\left(\mathrm{TiCl}_4\right)$.

The monomer units of nylon-6, 6 are hexamethylene diamine and adipic acid.

Buna-S is the co-polymer of but 1, 3-diene and styrene as follows.

Styrene butadiene rubber is also called buna-S, in which ‘Bu’ stands for butadiene, ‘na’ stands for sodium and ‘S’ stands for styrene.

Since, butadiene and styrene is one of the constituent monomer of given polymer.

Starch is a polymer of glucose. In sucrose, two monosaccharide (glucose) units are joined by $\alpha$-1, 2 glycoside bond.

Monomer is a molecule that forms the basic unit of polymer. These are building blocks of a polymer. Monomers bind to other monomer to form the repeating chain molecules. The monomers may be either natural or synthetic in origin monomer of melamine are,

$ \text { Hence, option (c) is the correct answer. } $

It is PHBV , i.e. poly- $\beta$-hydroxy butyrate-co- $\beta$-hydroxy valerate. It is a condensation, biodegradable and thermoplastic polyester (copolymer). So, statements I, II and IV are correct.

$\because$ Buna- S is $n \mathrm{CH}_2=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_2$

(1, 3-butadine) $+n \mathrm{C}_6 \mathrm{H}_5-\mathrm{CH}=\mathrm{CH}_2$ (styrene);

Buna- N is $n \mathrm{CH}_2=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_2$

All these are synthetic rubber.

Hence, option (c) is the correct answer, i.e. (ii), (iii) and (iv).