Concept:The physical state of a molecular substance at room temperature depends entirely on how tightly its molecules are bound together by intermolecular forces.
Formula:Not applicable.
Solution:- Hydrogen disulphide (\( \text{H}_2\text{S} \)) relies on weak dipole-dipole forces and is a gas.
- Ammonia (\( \text{NH}_3 \)) has hydrogen bonding, but each molecule only has one lone pair, limiting the network size, making it a gas at room temperature.
- Water (\( \text{H}_2\text{O} \)) is unique. Its oxygen atom has two highly polar hydrogens and two lone pairs. This allows every single water molecule to form up to four strong Hydrogen bonds, creating a massive, tight 3D cohesive network.
- This incredibly strong network requires substantial energy to break apart, maintaining water strictly in the liquid state at standard room temperature.
Why other options are incorrect:Water is a covalent compound. It lacks the metallic lattice required for metallic bonds, the electron transfer required for ionic bonds, and its state is not dictated by coordinate bonds.
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