xi. The synthesis of which of the following polymers require the loss of water molecules on a regular basis? (a) Polythene (b) Buma-N (c) Nylon-6,6 (d) Buna-S xii. The chemical added to detect leakage from LPG cylinder is (a) TEL (b) iso-octane (c) iso-butane (d) ethyl mercaptan xiii. The amount of electricity required to produce 12 gm of \( \mathrm{O}_{2} \) at respective electrode from acidulated water is- (a) 1 F (b) 2 F (c) 1.5 F (d) 0.5 F xiv. Oxidation number of O in \( \mathrm{H}_{2} \mathrm{O}_{2} \) is (a) -2 (b) +2 (c) -1 (d) +1 xv. Octane number of petrol is calculated considering the percentage of (a) Isoprene (b) iso-octane (c) n-hexadecane (d) iso-butane.

Sure, let's address each of your questions one by one: --- ### **xi. The synthesis of which of the following polymers require the loss of water molecules on a regular basis?** - **Options:** - (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, where hexamethylenediamine reacts with adipic acid, releasing water molecules as a byproduct. This type of polymerization typically involves the loss of small molecules like water or methanol. In contrast: - **Polythene** is produced via **addition polymerization**, which doesn't involve the loss of water. - **Buna-N** and **Buna-S** are types of synthetic rubber produced through the polymerization of butadiene with acrylonitrile or styrene, respectively. These processes are also **addition polymerizations** and do not release water. --- ### **xii. The chemical added to detect leakage from LPG cylinder is** - **Options:** - (a) TEL - (b) iso-octane - (c) iso-butane - (d) ethyl mercaptan **Answer:** **(d) Ethyl mercaptan** **Explanation:** **Ethyl mercaptan** is commonly added to LPG (Liquefied Petroleum Gas) because it has a strong, unpleasant odor. This makes it easier to detect gas leaks, ensuring safety. --- ### **xiii. The amount of electricity required to produce 12 gm of \( \mathrm{O}_{2} \) at respective electrode from acidulated water is** - **Options:** - (a) 1 F - (b) 2 F - (c) 1.5 F - (d) 0.5 F **Answer:** **(c) 1.5 F** **Explanation:** 1. **Calculate moles of \( \mathrm{O}_{2} \):** \[ \text{Molar mass of } \mathrm{O}_{2} = 32 \, \text{g/mol} \\ \text{Moles of } \mathrm{O}_{2} = \frac{12 \, \text{g}}{32 \, \text{g/mol}} = 0.375 \, \text{mol} \] 2. **Electrolysis of water:** \[ 2 \, \mathrm{H}_{2}\mathrm{O} \rightarrow 2 \, \mathrm{H}_{2} + \mathrm{O}_{2} \] For each mole of \( \mathrm{O}_{2} \), 4 Faradays (F) of charge are required (since each oxygen atom gains 2 electrons). 3. **Total charge required:** \[ 0.375 \, \text{mol} \times 4 \, \text{F/mol} = 1.5 \, \text{F} \] --- ### **xiv. Oxidation number of O in \( \mathrm{H}_{2}\mathrm{O}_{2} \) is** - **Options:** - (a) -2 - (b) +2 - (c) -1 - (d) +1 **Answer:** **(c) -1** **Explanation:** In hydrogen peroxide (\( \mathrm{H}_{2}\mathrm{O}_{2} \)), the oxidation state of each oxygen atom is **-1**. This is different from water (\( \mathrm{H}_{2}\mathrm{O} \)), where oxygen has an oxidation state of -2. --- ### **xv. Octane number of petrol is calculated considering the percentage of** - **Options:** - (a) Isoprene - (b) iso-octane - (c) n-hexadecane - (d) iso-butane **Answer:** **(b) iso-octane** **Explanation:** The **octane number** is a measure of a fuel's ability to resist "knocking" during combustion. It is defined using a scale where: - **Iso-octane** (\( 2,2,4\text{-Trimethylpentane} \)) is assigned an octane number of **100**. - **n-Heptane** is assigned an octane number of **0**. Therefore, the octane rating is determined based on the percentage of iso-octane in the fuel mixture. --- I hope these explanations help clarify your questions!