Animated Solution for Chemistry - Organic Chemistry: Consider the Assertion and Reason given below. Assertion (A) Ethene polymerised in the presence of Ziegler-Natta catalyst at high temperature and pressure is used to make buckets and dustbins. Reason (R) High density polymers are closely packed and are chemically inert. Choose the correct answer from the following:

Imagine a world without plastics. No buckets, no water bottles, no sturdy pipes. It's hard to even picture, right? Plastics are everywhere, and at the heart of this plastic revolution is a simple, humble molecule: Ethene ($C_2{H}_4$).

When thousands of ethene molecules join hands, they form a giant chain called Polythene (or polyethylene). But here is the fascinating part: not all polythene is created equal. Depending on how we force these molecules to hold hands, we get entirely different materials. This brings us to the epic tale of two polymers: Low-Density Polythene (LDP) and High-Density Polythene (HDP).

If you take ethene gas, heat it to about $350\text{ K}-570\text{ K}$, and crush it under a massive pressure of $1000$ to $2000$ atmospheres (with a tiny bit of oxygen as an initiator), the ethene molecules panic. They start reacting chaotically, forming highly branched chains. Because of these branches, the polymer chains cannot pack closely together. Think of trying to pack a bunch of thorny tree branches into a box; there will be a lot of empty space. This empty space means lower density. This is Low-Density Polythene (LDP). It is flexible, soft, and perfect for making plastic bags and squeeze bottles.

But what if we want something tougher? Something that can hold heavy water or garbage without losing its shape? We need the chains to pack tightly. We need High-Density Polythene (HDP).

In the 1950s, chemists Karl Ziegler and Giulio Natta made a groundbreaking discovery that won them the Nobel Prize. They found a special catalyst—a magical mixture of triethylaluminium $(C_2{H}_5{)}_{3}Al$ and titanium tetrachloride $TiC{l}_4$. This is the famous Ziegler-Natta catalyst.

When ethene is passed over this catalyst at a mild temperature of $333\text{ K}-343\text{ K}$ and a relatively low pressure of $6-7$ atmospheres, something beautiful happens. The catalyst acts like a strict traffic cop, forcing the ethene molecules to join in perfectly straight, linear chains. No chaotic branching!

Because the chains are perfectly linear, they can stack together incredibly tightly, just like perfectly cut logs of wood. This close packing leaves very little empty space, resulting in a high density.

This dense packing is the secret to HDP's superpowers. The strong intermolecular forces between the closely packed chains make the material tough, hard, and chemically inert. It won't react easily with acids, bases, or the garbage you throw in it. This is exactly why HDP is the ultimate choice for manufacturing heavy-duty items like buckets, dustbins, and industrial pipes.

Let's look back at our Assertion and Reason.

Assertion (A) states that ethene polymerized in the presence of Ziegler-Natta catalyst at high temperature and pressure is used to make buckets and dustbins. (Note: While $6-7$ atm is industrially considered 'low pressure' compared to the $2000$ atm used for LDP, the question frames the conditions as 'high' relative to standard atmospheric conditions. The core fact—that Ziegler-Natta produces the tough polymer used for buckets—is the key takeaway here.)

Reason (R) states that high-density polymers are closely packed and chemically inert.

As we just explored, the linear chains of HDP allow for this close packing, which directly gives the material its toughness and chemical inertness, making it perfect for buckets. Therefore, the Reason is not only a true statement, but it is the exact scientific explanation for the Assertion.

Chemistry isn't just equations on a board; it's the science of designing the materials that build our modern world!