The correct match between Item - I and Item - II is :
Item - I
(A) Natural rubber
(B) Neoprene
(C) B

Q: What does 'Buna' stand for?

'Bu' stands for 1,3-butadiene, and 'na' stands for Natrium (Sodium), which is used as a catalyst in the polymerization process.

Q: How is Neoprene different from Natural Rubber?

Natural rubber is a polymer of isoprene (2-methyl-1,3-butadiene), whereas neoprene is a polymer of chloroprene (2-chloro-1,3-butadiene). The methyl group is replaced by a chlorine atom, giving neoprene better chemical stability.

Q: Are Buna-N and Buna-S addition or condensation polymers?

They are addition polymers, specifically copolymers, formed by the addition of two different monomers without the loss of any small molecules.

Q: Why is sodium used in the preparation of Buna rubbers?

Sodium acts as a catalyst to initiate the free radical or anionic polymerization of the diene monomers.

Q: Is Natural Rubber a homopolymer or copolymer?

Natural rubber is a homopolymer because it is made up of only one type of monomer unit, which is isoprene.

Question

The correct match between Item - I and Item - II is :
\begin{array}{llll}
& 	extbf{Item - I} & & 	extbf{Item - II} \
	ext{(A)} & 	ext{Natural rubber} & 	ext{(I)} & 	ext{1,3- butadiene + styrene} \
	ext{(B)} & 	ext{Neoprene} & 	ext{(II)} & 	ext{1,3- butadiene + acrylonitrile} \
	ext{(C)} & 	ext{Buna -N} & 	ext{(III)} & 	ext{Chloroprene} \
	ext{(D)} & 	ext{Buna -S} & 	ext{(IV)} & 	ext{Isoprene}
\end{array}

Options:

(A) (A)-(III), (B)-(IV), (C)-(I), (D)-(II)

(B) (A)-(III), (B)-(IV), (C)-(II), (D)-(I)

(C) (A)-(IV), (B)-(III), (C)-(II), (D)-(I)

(D) (A)-(IV), (B)-(III), (C)-(I), (D)-(II)

Sigma Percentile · Accepted Answer

### The Art of Decoding Polymers

Have you ever looked at a list of chemical names and felt overwhelmed? It is a common feeling, but here is a secret: chemists are actually very logical people.

Most synthetic polymers have their entire recipe hidden right inside their names!

In this problem, we are tasked with matching four famous polymers—Natural Rubber, Neoprene, Buna-N, and Buna-S—with their monomeric building blocks. Let's break them down one by one and see how beautifully simple this can be.

### Natural Rubber and Neoprene: The Diene Twins

Let's start with **Natural Rubber**. Imagine the sticky, milky latex dripping from a rubber tree.

Nature builds this incredible material using a single, repeating unit called **isoprene**. Chemically, isoprene is known as $2$-methyl-$1,3$-butadiene.

$$n 	ext{CH}_2=	ext{C}(	ext{CH}_3)-	ext{CH}=	ext{CH}_2 \longrightarrow 	ext{Polyisoprene}$$

So, Natural Rubber (A) pairs perfectly with Isoprene (IV).

Now, what if we want to make a synthetic version of rubber that is more resistant to chemicals and heat? We tweak the recipe slightly!

Enter **Neoprene**. Instead of a methyl group, we attach a highly electronegative chlorine atom to the diene backbone.

This gives us **chloroprene**, or $2$-chloro-$1,3$-butadiene.

$$n 	ext{CH}_2=	ext{C}(	ext{Cl})-	ext{CH}=	ext{CH}_2 \longrightarrow 	ext{Neoprene}$$

Therefore, Neoprene (B) matches with Chloroprene (III).

### Decoding the "Buna" Family

Now we encounter the synthetic rubbers developed during the early 20th century: Buna-N and Buna-S.

The word "Buna" is not just a random name; it is an acronym!

The **"Bu"** stands for **$1,3$-butadiene**, which forms the main carbon backbone. The **"na"** stands for **Natrium** (the Latin name for Sodium), which acts as the catalyst to kickstart the polymerization.

So, what about the letters at the end? They tell us the comonomer!

For **Buna-N**, the **"N"** stands for **Nitrile**, specifically acrylonitrile.

This means Buna-N is a copolymer of $1,3$-butadiene and acrylonitrile.

Thus, Buna-N (C) matches with $1,3$-butadiene + acrylonitrile (II).

Similarly, for **Buna-S**, the **"S"** stands for **Styrene**.

This makes Buna-S a copolymer of $1,3$-butadiene and styrene.

Consequently, Buna-S (D) matches with $1,3$-butadiene + styrene (I).

### The Final Verdict

We have successfully decoded all four polymers. Let's summarize our findings:

(A) Natural Rubber $\longrightarrow$ (IV) Isoprene
(B) Neoprene $\longrightarrow$ (III) Chloroprene
(C) Buna-N $\longrightarrow$ (II) $1,3$-butadiene + acrylonitrile
(D) Buna-S $\longrightarrow$ (I) $1,3$-butadiene + styrene

Looking at our options, this exact sequence corresponds to **Option (c)**.

By simply understanding the nomenclature and the structural relationships, a seemingly complex memory-based question becomes a logical puzzle that is easy to solve!

Select Answer:

Visualized Solution

$Polymer-Monomer Matching$

$Natural Rubber$

$Neoprene$

$Buna-N$

$Buna-S$

$Final Conclusion$

The Sigma Insight: Polymers

The Art of Decoding Polymers

Natural Rubber and Neoprene

Decoding the "Buna" Family

The Final Verdict

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