Setting and hardening of cement involves (a) hydrolysis and neutralization (b)hydration and neutralization (c) hydration and hydrolysis (d) dehydration and hydrolysis. The synthesis of which of the following polymers require the loss of water molecules on a regular basis? (a) Polythene (b) Buna-N (c) Nylon-6,6 (d) Buna-S The chemical added to detect leakage from LPG cylinder is (a) TEL (b) iso-octane

Certainly! Let's address each of your multiple-choice questions one by one: --- ### **1. Setting and Hardening of Cement** **Question:** Setting and hardening of cement involves: - **(a)** Hydrolysis and Neutralization - **(b)** Hydration and Neutralization - **(c)** Hydration and Hydrolysis - **(d)** Dehydration and Hydrolysis **Answer:** **(c) Hydration and Hydrolysis** **Explanation:** The setting and hardening of cement primarily involve **hydration**, which is the chemical reaction between cement and water leading to the formation of various hydration products that give cement its strength. **Hydrolysis** also plays a role in breaking down some of the minerals in cement, contributing to the hardening process. --- ### **2. Polymer Synthesis Requiring Loss of Water Molecules** **Question:** The synthesis of which of the following polymers requires the loss of water molecules on a regular basis? - **(a)** Polythene - **(b)** Buna-N - **(c)** Nylon-6,6 - **(d)** Buna-S **Answer:** **(c) Nylon-6,6** **Explanation:** **Nylon-6,6** is synthesized through a condensation polymerization process, which involves the loss of water molecules as by-products during the formation of amide bonds between monomers. This characteristic distinguishes it from polymers like Polythene, Buna-N, and Buna-S, which are typically formed through addition polymerization without the elimination of small molecules like water. --- ### **3. Chemical Added to Detect Leakage from LPG Cylinder** **Question:** The chemical added to detect leakage from LPG cylinders is: - **(a)** TEL - **(b)** Iso-octane **Answer:** **(a) TEL (Tetraethyl Lead)** **Explanation:** **TEL (Tetraethyl Lead)** is traditionally used as an additive to detect gas leaks due to its strong odor, which makes it easier to identify leaks. While TEL has largely been phased out in many applications due to environmental and health concerns, in the context of the given options, TEL is the more appropriate choice for leak detection compared to Iso-octane. --- **Note:** It's important to highlight that in modern applications, other odorants like **ethyl mercaptan** are commonly used for leak detection in LPG cylinders instead of TEL, which is toxic and has significant environmental impacts. --- I hope this clarifies your queries! If you have any more questions or need further explanations, feel free to ask.