Let's analyze each pair and select the more water-soluble compound. **Key concept:** Water solubility increases with the presence of polar groups (like OH, NH₂, COOH) that can hydrogen bond with water. --- ### (a) **CH₂Cl₂** or **CH₃OH** - **CH₂Cl₂** (dichloromethane): Moderately polar, can't hydrogen bond with water. - **CH₃OH** (methanol): Highly polar, can hydrogen bond. - **More soluble:** **CH₃OH** (methanol) --- ### (b) **CH₃COCH₃** or **CH₃CH₂CH₃** - **CH₃COCH₃** (acetone): Contains a carbonyl group (C=O), polar, can hydrogen bond as an acceptor. - **CH₃CH₂CH₃** (propane): Non-polar hydrocarbon. - **More soluble:** **CH₃COCH₃** (acetone) --- ### (c) **CH₃CH₂Cl** or **NaCl** - **CH₃CH₂Cl** (ethyl chloride): Slightly polar, limited solubility. - **NaCl** (sodium chloride): Ionic, **very** soluble in water. - **More soluble:** **NaCl** --- ### (d) -  (**SH group**) -  (**OH group**) - **2-propanethiol**: Contains –SH group, less able to hydrogen bond. - **2-propanol**: Contains –OH group, can strongly hydrogen bond. - **More soluble:** **2-propanol** (with –OH) --- ### (e) -  (**OH group**) -  (**C=O group**) - **2-pentanol**: Contains –OH group, can donate and accept H-bonds. - **2-pentanone**: Contains C=O, can only accept H-bonds. - **More soluble:** **2-pentanol** (with –OH) --- ## **Summary Table** | Pair | More Water-Soluble | |-----------|----------------------------| | (a) | CH₃OH | | (b) | CH₃COCH₃ (acetone) | | (c) | NaCl | | (d) | 2-propanol (with –OH) | | (e) | 2-pentanol (with –OH) | --- **Reason:** Compounds with –OH, ionic character, or polar groups that can hydrogen bond are generally more soluble in water.

# Underground Power Cable Insulation When it comes to underground power cables, insulation is essential for safe and reliable operation. One key aspect of insulation is managing electric stress to prevent failures. ## Methods to Distribute Electric Field ### Common Techniques - **Cable Grading**: This involves using conductive layers to create a more uniform electric field across the insulation, thereby reducing maximum electric stress. - **Corona Shielding**: Primarily used for overhead lines, it helps prevent corona discharge but is not directly related to underground cable insulation. - **Insulation Coordination**: Ensures that the insulation levels are appropriate for the voltage and environmental conditions, but does not specifically focus on electric stress distribution. - **Stress Shielding**: This technique uses conductive materials to mitigate stress concentrations in the insulation. ## Answer to the Question The method used to reduce maximum electric stress in cable insulation by providing conductive layers is known as: ### **A. Cable Grading**