Q. Water can dissolve more substances than any other liquid because (UPSC Prelims 2021)
Answer:
it is dipolar in nature
Notes: The correct answer is
[A] it is dipolar in nature. Water is often called the "universal solvent" because it dissolves more substances than any other liquid due to its unique chemical structure.
- Dipolar Nature (Correct): A water molecule (H2O) is polar because of the difference in electronegativity between hydrogen and oxygen. The oxygen atom carries a partial negative charge (δ⁻), while the hydrogen atoms carry partial positive charges (δ⁺). This creates a "dipole."
- Mechanism: When an ionic or polar substance is placed in water, the partial charges of the water molecules attract the ions or molecules of the solute. For example, in common salt (NaCl), the positive ends of water molecules attract the chloride ions (Cl^-) and the negative ends attract the sodium ions (Na^+), pulling them apart and dissolving the crystal.
- Good Conductor of Heat [B] (Incorrect): While water conducts heat better than many other liquids, this property relates to energy transfer (thermal conductivity), not its ability to break chemical bonds for dissolution.
- High Specific Heat [C] (Incorrect): This refers to the amount of heat required to raise the temperature of water by 1°C. While this property is vital for climate regulation and biological homeostasis, it does not explain its solvent power.
- Oxide of Hydrogen [D] (Incorrect): Water is indeed an oxide of hydrogen, but many other oxides (like carbon dioxide or iron oxide) do not possess the same solvent properties. The "oxide" classification doesn't inherently grant the ability to dissolve substances.